Magnetic suspension centrifuge, storage medium, high-power frequency converter and control method thereof

Abstract

The present invention discloses a magnetic levitation centrifuge, a storage medium, a high-power frequency converter and a control method thereof. The frequency converter comprises a main circuit: connected to a load and powered for the load, comprising a rectifier module and a bus capacitor; a control circuit: connected to the main circuit and the load, powered by the main circuit and controlling the load to start; a charging circuit: connected to the main circuit, used to protect the main circuit when powered on; a voltage acquisition circuit: connected to the charging circuit and the control circuit, used to acquire a voltage signal Vr of the charging circuit and feed the voltage signal Vr back to the control circuit, and the control circuit controls the rectifier module according to the voltage signal Vr. The magnetic levitation centrifuge, storage medium, high-power frequency converter and a control method thereof of the present invention effectively solve the phenomenon of IGBT malfunction caused by interference at the moment when the frequency converter is powered on, and avoid safety accidents caused by heating of the charging resistor.

Description

Technical Field

[0001] The present invention relates to the technical field of high-power frequency converters, and in particular to a magnetic suspension centrifuge, a storage medium, a high-power frequency converter and a control method thereof. Background Art

[0002] In high-power inverters, in order to limit the impact on the bus capacitor during the power-on process, a charging circuit is added outside the main circuit. The charging circuit consists of three ripple resistors and a circuit breaker. The power-on method is to first close the circuit breaker in the soft start circuit and charge the inverter bus through the charging resistor. When the bus voltage is greater than 400V, the DC-DC power supply will be able to work, thereby outputting 24V voltage to power the control circuit. After the control circuit is powered, the bus voltage will be detected. When the bus voltage is greater than 450V, a control command will be issued to the circuit breaker in the main circuit. At this time, circuit breaker 1 meets the closing conditions and the inverter enters the waiting-for-closing start state.

[0003] During the power-on process of the inverter, the inverter power devices are powered on first with strong power and then with weak power (control power). Therefore, during the interval between the power-on of strong power and weak power, the control signal of the IGBT is in a state that is easily interfered with, and the IGBT may have a mis-conduction problem. Subsequently, the charging resistor may have an overcurrent phenomenon. If the main circuit is not closed in time, the charging resistor will heat up seriously, causing hidden dangers.

[0004] Patent No. CN105871191A discloses a device and method for suppressing the power-on surge current of a three-phase power source type PWM module rectifier. It proposes a controllable damping circuit design for power-on surge. However, its detection circuit design is complex and its reliability is reduced in an environment with strong electromagnetic interference. Summary of the invention

[0005] The object of the present invention is to overcome the deficiencies in the prior art and to provide a magnetic suspension centrifuge, a storage medium, a high-power frequency converter and a control method thereof.

[0006] In a first aspect, the present invention provides a high-power frequency converter, the frequency converter comprising:

[0007] Main circuit: connects to the load and supplies power to the load, including rectifier module and bus capacitor;

[0008] Control circuit: connecting the main circuit and the load, supplying power through the main circuit and controlling the load to start;

[0009] Charging circuit: connected to the main circuit, used to protect the main circuit when powered on;

[0010] Voltage acquisition circuit: connected to the charging circuit and the control circuit, used for acquiring the voltage signal Vr of the charging circuit and feeding the voltage signal Vr back to the control circuit, and the control circuit controls the rectifier module according to the voltage signal Vr.

[0011] Preferably, the main circuit further includes a first circuit breaker, and the charging circuit includes a second circuit breaker and a charging resistor.

[0012] Preferably, the frequency converter also includes a bus voltage acquisition circuit, a first circuit breaker control circuit and a second circuit breaker control circuit, the bus voltage acquisition circuit connects the bus and the control circuit, the first circuit breaker control circuit connects the control circuit and the first circuit breaker, and the second circuit breaker control circuit connects the controller and the second circuit breaker.

[0013] Preferably, the control circuit includes a rectifier main control board, a DC-DC power supply and an inverter main control board, and the rectifier main control board includes a plurality of IGBT modules and a drive board corresponding to the IGBT modules.

[0014] In a second aspect, the present invention further provides a control method for a high-power frequency converter, and the control method is implemented by the high-power frequency converter described in the first aspect.

[0015] Preferably, a first embodiment of the control method of the high-power inverter includes:

[0016] Obtaining a voltage value Vr of the charging resistor;

[0017] When the voltage value Vr of the charging resistor is greater than the preset threshold voltage Vr′, the rectifier main control board sends out pulses to turn off the IGBT modules in sequence.

[0018] Preferably, the rectifier main control board sends pulses to turn off the IGBT modules in sequence specifically:

[0019] When the voltage value Vr of the charging resistor is greater than a preset threshold voltage Vr′, the PWM module is set to an independent mode;

[0020] After a delay of n seconds, the rectifier main control board sends out pulses to turn off the IGBT modules in sequence.

[0021] Preferably, the first embodiment of the control method of the high-power inverter further includes the following steps:

[0022] Set the PWM module to complementary mode;

[0023] Start normally;

[0024] The inverter enters the state of waiting for closing and starting.

[0025] Preferably, after the delay of n seconds, the rectifier main control board sends a pulse to turn off the IGBT modules in sequence, and the delay time is specifically 5 seconds.

[0026] Preferably, the second embodiment of the control method of the high-power inverter includes:

[0027] The inverter is powered on, and the bus capacitor starts to charge;

[0028] The control circuit is powered on and initialized;

[0029] The main rectifier control board initializes all the IGBT modules simultaneously.

[0030] Preferably, the second embodiment of the control method of the high-power inverter further includes:

[0031] After all the IGBT modules are initialized, all the IGBT modules are stably turned off to ensure the normal operation of the rectifier module;

[0032] The inverter enters the state of waiting for closing and starting.

[0033] Preferably, a third embodiment of the control method of the high-power inverter includes:

[0034] The inverter is powered on, and the bus capacitor starts to charge;

[0035] The rectifier main control board starts the internal timer after being powered on;

[0036] When the timing time reaches the preset time t, the rectifier main control board controls the second circuit breaker to open and controls the first circuit breaker to close;

[0037] The inverter enters the waiting state.

[0038] Preferably, the fourth embodiment of the control method of the high-power inverter includes:

[0039] The inverter is powered on, and the bus capacitor starts to charge;

[0040] The rectifier main control board obtains a voltage signal Vc at both ends of the bus capacitor after being powered;

[0041] When the voltage signal Vc across the bus capacitor is stable, the rectifier main control board controls the second circuit breaker to open, and at the same time controls the first circuit breaker to close;

[0042] The inverter enters the waiting state.

[0043] In a third aspect, the present invention further provides a magnetic levitation centrifuge, wherein the magnetic levitation centrifuge comprises the high-power frequency converter described in the first aspect.

[0044] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the control method described in any one of the embodiments in the second aspect.

[0045] The beneficial effects of the present invention are as follows: the present invention provides a high-power frequency converter, a control method, a compressor and a storage medium. The present invention determines whether there is an IGBT malfunction phenomenon by detecting the voltage drop across the charging resistor. If it is detected that the voltage U is greater than the comparison voltage, the rectifier main control board will forcefully send a PWM narrow pulse signal to turn off the IGBT, thereby avoiding heating caused by a large current flowing through the resistor for a long time; the phenomenon of IGBT malfunction caused by interference at the moment when the frequency converter is powered on is effectively solved, thereby avoiding safety accidents caused by heating of the charging resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0047] Figure 1 It is an electrical topology diagram of a high-power frequency converter according to an embodiment of the present invention.

[0048] Figure 2 It is a circuit structure diagram of a rectifier module in a high-power inverter power-on circuit according to an embodiment of the present invention.

[0049] Figure 3 It is a circuit structure diagram of a driving board of a rectifier module in a power-on circuit of a high-power inverter according to an embodiment of the present invention.

[0050] Figure 4 It is a flow chart of a control method for a power-on circuit of a high-power frequency converter according to Embodiment 1 of the present invention.

[0051] Figure 5 It is a flow chart of a control method for a high-power inverter power-on circuit according to Embodiment 2 of the present invention.

[0052] Figure 6 It is an abnormal waveform diagram of the power-on circuit of the high-power inverter according to the first embodiment of the present invention.

[0053] Figure 7 This is an abnormal waveform diagram during the power-on process of the high-power inverter power-on circuit of Example 1 of the present invention.

[0054] Figure 8 It is a waveform diagram of the implementation effect of the high-power inverter power-on circuit of Example 1 of the present invention.

[0055] The reference numerals are as follows: 10. main circuit, 20. charging circuit, 30. control circuit, 40. load. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0057] Embodiment 1, a high-power frequency converter.

[0058] As attached Figure 1 As shown, a high-power frequency converter of this embodiment includes:

[0059] Main circuit 10: connected to load 40 and supplies power to load 40, including a rectifier module, a bus capacitor, a first circuit breaker and an inverter module;

[0060] Control circuit 30: connected to the main circuit 10 and the load 40, powered by the main circuit 10 and controlling the load 40 to start, including a rectifier main control board, a DC-DC power supply, an inverter main control board and a bearing controller, wherein the rectifier main control board includes a main control chip DSP, a processor and a memory;

[0061] Charging circuit 20: connected to the main circuit 10, used to protect the main circuit 10 when powered on, including a second circuit breaker and a charging resistor;

[0062] Voltage acquisition circuit: connected to the charging circuit 20 and the control circuit 30, used for acquiring the voltage signal Vr of the charging circuit 20 and feeding the voltage signal Vr back to the control circuit 30, and the control circuit 30 controls the rectifier module according to the voltage signal Vr.

[0063] The high-power frequency converter of this embodiment can be used for a variety of high-power equipment, such as motors, compressors, large refrigeration tonnage magnetic suspension units, magnetic suspension centrifuges, etc. This embodiment is described by taking the magnetic suspension centrifuge as an example. In this embodiment, the load 40 is the motor and magnetic suspension bearing in the magnetic suspension centrifuge.

[0064] Among them, as attached Figure 2As shown, the rectifier module includes six IGBTs, six corresponding drive boards, six corresponding diodes and a filter capacitor CY, the positive electrodes of the six diodes are connected to the emitters of the corresponding six IGBTs, the negative electrodes of the six diodes are connected to the collectors of the corresponding six IGBTs, the first ports of the six drive boards are all connected to the rectifier main control board, the second ports of the six drive boards are all connected to the gates of the six corresponding IGBTs, the third ports of the six drive boards are all connected to the emitters of the corresponding IGBTs, the emitters of the first IGBT, the second IGBT and the third IGBT are respectively connected to the U, V and W phases of the three-phase electricity and the common ends are respectively connected to the collectors of the fourth IGBT, the fifth IGBT and the sixth IGBT, the collectors of the first IGBT, the second IGBT and the third IGBT are commonly connected to the positive output terminal DC+ of the rectifier module, the emitters of the fourth IGBT, the fifth IGBT and the sixth IGBT are commonly connected to the negative output terminal DC- of the rectifier module, and the two ends of the filter capacitor CY are respectively connected to the positive output terminal DC+ and the negative output terminal DC- of the rectifier module.

[0065] Among them, the first IGBT, the second IGBT, and the third IGBT are upper bridge arms, and the fourth IGBT, the fifth IGBT, and the sixth IGBT are lower bridge arms.

[0066] The driving board IPM drives the pulse transformer, and the input end of the IPM drives the pulse transformer is connected to the rectifier main control board, and the output end of the IPM drives the pulse transformer is connected to the control end of the IGBT. When the IPM pulse transformer detects an upward edge change at the input end, it will output a high level, and this level signal will drive the IGBT to turn on; when the IPM pulse transformer detects a downward edge change at the input end, it will output a low level, and this level signal will drive the IGBT to turn off.

[0067] From the rectifier module, we know that the driving ground of the three-phase lower bridge arm is the same ground. Since the emitters of the three-phase upper bridge arm are the three-phase input U, V, and W respectively, the driving ground of the upper bridge arm cannot be shared, and is a virtual ground, which is more susceptible to interference (such as the attached Figure 6 as shown).

[0068] As attached Figure 7 As shown in the figure, at the moment the inverter is powered on, due to the existence of bus capacitance,

[0069] i=C*(du / dt)

[0070] It can be seen that it will cause a current spike, and the changing current will produce a changing magnetic field. The EMI signal generated by the changing magnetic field will interfere with the upper bridge arm drive ground. After the IPM pulse transformer inside the driver board detects that the jump signal will output a high level, it will latch the high level signal and drive the upper bridge arm IGBT of this phase to turn on. Since the interference signal does not have a falling edge jump signal, the IPM pulse transformer will not generate a low level signal, resulting in the IGBT being unable to turn off. The continuous opening of the IGBT will destroy the original three-phase symmetrical working sequence, causing a continuous large current (abnormally about 1.2A, normal charging current about 0.2A) to flow through the charging resistor in the charging circuit 20 of this phase. By

[0071] Q=I^2 R

[0072] It can be seen that under long-term abnormal charging conditions, the charging resistor will generate a lot of heat, posing a safety hazard. In serious cases, it may cause safety accidents such as fire.

[0073] In this embodiment, the voltage acquisition circuit includes a comparator, one input end of the comparator is connected to the charging circuit 20, the other input end of the comparator is connected to a power supply, the voltage of the power supply is equal to a preset threshold voltage Vr′, and the output end of the comparator is connected to the first I / O port of the rectifier main control board. According to the selection of the input end of the comparator, when the voltage Vr of the charging resistor is greater than the threshold voltage Vr′, the comparator can output a high-level or low-level overheat signal to the rectifier main control board. For example, when the voltage Vr of the charging resistor is greater than the threshold voltage Vr′, the comparator outputs a high-level overheat signal to the rectifier main control board.

[0074] The working principle and beneficial effects of this embodiment are as follows: Figure 8 As shown, after the inverter is powered on, the bus capacitor starts to charge. When the voltage acquisition circuit detects that the charging circuit 20 is abnormal, it outputs a high-level overheat signal to the rectifier main control board. The main control chip DSP of the rectifier main control board will first set the PWM module to independent mode. After a delay of 5s, the main control chip will sequentially send out narrow pulse signals of the PWM module. The narrow pulse signal has a complete rising edge and a falling edge. The falling edge is input to the IGBT driver board to force the IGBT module to shut down, and then the PWM module is set to complementary mode. After entering the complementary mode, the inverter starts normally. When the bus capacitor is charged, the inverter enters the waiting-for-closing start mode. The inverter enters the charging resistor so as to keep the inverter charged by the charging circuit 20, and the charging resistor will not cause a safety hazard due to overheating.

[0075] Example 2.

[0076] like Figure 4 As shown, this embodiment provides a control method for a high-power inverter, and the control method is implemented by the high-power inverter described in Example 1, including:

[0077] Get the voltage value Vr of the charging resistor;

[0078] The real-time voltage value of the charging resistor is obtained through the voltage acquisition circuit.

[0079] When the voltage value Vr of the charging resistor is greater than the preset threshold voltage Vr′, the PWM module is set to an independent mode;

[0080] The voltage acquisition circuit includes a comparison circuit. When the voltage value Vr of the charging resistor is greater than the preset threshold voltage Vr′, the voltage acquisition circuit outputs a high-level overheat signal to the main control chip DSP of the rectifier main control board. After the main control chip DSP obtains the overheat signal, it sets the PWM module to independent mode.

[0081] After a delay of n seconds, the main rectifier control board sends out pulses to turn off the IGBT modules one by one;

[0082] Specifically, the delay time n is 5 seconds;

[0083] After testing, the fault usually reappears about 200ms after power-on, leaving some margin, and the pulse signal can be sent after 1s.

[0084] However, the interval cannot be too long, as continuous heating may cause hidden dangers, so in this embodiment, the delay time n is set to 5 seconds. After the PWM module of the main control chip DSP is set to independent mode, it waits for 5 seconds before sending a pulse to the control end of each IGBT. The pulse signal has a complete rising edge and falling edge, so that all IGBTs are turned off.

[0085] Set the PWM module to complementary mode;

[0086] Start normally;

[0087] The inverter enters the state of waiting for closing and starting.

[0088] After all IGBTs are turned off, the PWM module mode of the main control chip DSP is set to complementary mode again to enable the inverter to start normally. After the inverter starts normally, the bus capacitor continues to charge. When the bus capacitor is fully charged, the inverter enters the waiting-for-closing start state.

[0089] When the inverter is powered on, the bus capacitor in the inverter needs to be charged through the charging circuit 20, and this process takes a certain amount of time. At this time, the output voltage of the inverter is an unstable voltage, and this unstable voltage cannot drive the motor to work. Only when the bus capacitor of the inverter is fully charged, the output voltage of the inverter is stable. At this time, the output voltage of the inverter can directly drive the motor to work. At this time, the circuit breaker of the main circuit 10 of the inverter can be closed, and the inverter voltage can directly start the motor. Therefore, when the bus capacitor of the inverter is fully charged, the inverter enters the state of waiting for closing and starting.

[0090] The working principle and beneficial effects of this embodiment: a voltage acquisition circuit is added at both ends of the charging resistor, and the voltage acquisition circuit is used to determine whether the charging resistor is abnormal. When the charging resistor is abnormal, the main control chip DSP will first set the PWM module to independent mode, and after a delay of 5s, the main control chip will sequentially send out narrow pulse signals of the PWM module. The narrow pulse signal has a complete rising edge and a falling edge. The falling edge is input to the IGBT driver board to force the IGBT module to shut down. This effectively shuts down the IGBT module and avoids safety accidents caused by excessive charging current for a long time.

[0091] Example 3.

[0092] like Figure 5 As shown, this embodiment provides a control method for a high-power inverter, and the control method is implemented by the high-power inverter described in Example 1, including:

[0093] When the three-phase input power is first connected to the inverter, the bus capacitor begins to charge;

[0094] After the inverter is powered on normally, the bus capacitor starts to charge. When the bus voltage reaches the minimum operating threshold voltage of the DC / DC switching power supply, the DC / DC switching power supply supplies power to the rectifier main control board and the motor inverter main control board, and the rectifier main control board and the motor inverter main control board are connected to the inverter system.

[0095] The control circuit 30 is powered on and initialized;

[0096] After the rectifier main control board is powered on, the main control chip DSP is initialized first.

[0097] The rectifier main control board initializes each IGBT;

[0098] After IGBT initialization is completed, all IGBTs are turned off stably to ensure the normal operation of the rectifier module;

[0099] After the main control chip DSP is initialized, the main control chip DSP will initialize the IGBT of each bridge arm in turn, that is, send narrow pulses to the IGBT of each bridge arm in turn. Since the narrow pulse signal has a complete rising edge and a falling edge, the falling edge is input to the control end of the IGBT driver board. When the pulse transformer powered on the driver board detects the rising edge of the level, its back-end output level is high; when the falling edge of the level is detected, its back-end output is low.

[0100] Each IGBT is then controlled to perform a complete opening and closing action, ensuring that the IGBT is in a controllable and stable state during the process of the inverter charging and cutting into the main circuit 10, regardless of whether the charging resistor overheats.

[0101] The inverter enters the state of waiting for closing and starting.

[0102] The working principle and beneficial effects of this embodiment are as follows: the three-phase input power is first connected to the inverter system. When the bus voltage rises to the minimum working threshold of the DC / DC switching power supply, the inverter rectifier and inverter main control board control power is then connected to the inverter system. After the main control board is powered on, each bridge arm is initialized in turn, that is, by sending narrow pulses, the IGBT of each bridge arm is given a stable opening and closing process. Even if the interference during the inverter power-on process causes a certain bridge arm to be in a normally open state, when the PFC main control board completes the initialization of the IGBT, the abnormal IGBT will be stably turned off. Thereby, the rectifier module is restored to a three-phase symmetrical normal working state.

[0103] Example 4.

[0104] The present embodiment provides a control method for a high-power inverter. The difference between the high-power inverter that implements the control method of the present embodiment and the inverter of Embodiment 1 is that the high-power inverter of the present embodiment also includes a first circuit breaker control circuit 30 and a second circuit breaker control circuit 30. The first circuit breaker control circuit 30 connects the second I / O port of the control circuit 30 and the first circuit breaker, and the second circuit breaker control circuit 30 connects the third I / O port of the controller and the second circuit breaker.

[0105] The first circuit breaker control circuit 30 controls the on and off of the first circuit breaker according to the input signal, and the second circuit breaker control circuit 30 controls the on and off of the second circuit breaker according to the input signal. For example, when the first circuit breaker control circuit 30 inputs a high level, the first circuit breaker control circuit 30 controls the first circuit breaker to be turned on; when the first circuit breaker control circuit 30 inputs a low level, the first circuit breaker control circuit 30 controls the first circuit breaker to be turned off, and the control logic of the second circuit breaker control circuit 30 is the same as that of the first circuit breaker control circuit 30. The level signals output by the first circuit breaker control circuit 30 and the second circuit breaker control circuit 30 cannot be the same.

[0106] The control method of the high-power inverter includes:

[0107] The inverter is powered on and the bus capacitor starts to charge;

[0108] After the inverter is powered on normally, the bus capacitor starts to charge. When the bus voltage reaches the minimum operating threshold voltage of the DC / DC switching power supply, the DC / DC switching power supply supplies power to the rectifier main control board and the motor inverter main control board.

[0109] After the rectifier main control board is powered on, the internal timer is started;

[0110] After the rectifier main control board is powered on, the initialization operation is started first. After the initialization is completed, the internal timer in the main control chip DSP is started to start timing.

[0111] When the timing time reaches the preset time t, the rectifier main control board controls the second circuit breaker to open and controls the first circuit breaker to close;

[0112] When the timing time reaches the preset time t, the main control chip DSP outputs a low level to the third I / O port to open the second circuit breaker, and simultaneously outputs a high level to the second I / O port to close the first circuit breaker.

[0113] The inverter enters the waiting-to-start state;

[0114] The first circuit breaker is closed and the second circuit breaker is opened, so that the charging circuit 20 of the inverter is disconnected, the main circuit 10 is turned on, and the inverter enters the waiting-to-start state.

[0115] The working principle and beneficial effects of this embodiment are as follows: After the rectifier main control board is powered, the charging time is counted by the internal timer of the main control chip DSP. When the preset time t is reached, the second circuit breaker is automatically disconnected, the first circuit breaker is closed, and the inverter enters the waiting state. This prevents the inverter from being in the charging state for a long time, thereby avoiding the possible three-phase rectification imbalance problem and charging resistor overheating problem caused by IGBT misconduction.

[0116] Example 5.

[0117] The present embodiment provides a control method for a high-power inverter. The difference between the high-power inverter that implements the control method of the present embodiment and the inverter of Embodiment 1 is that the inverter of the present embodiment also includes a bus voltage acquisition circuit, a first circuit breaker control circuit 30 and a second circuit breaker control circuit 30. The bus voltage acquisition circuit connects the bus and the control circuit 30, the first circuit breaker control circuit 30 connects the control circuit 30 and the first circuit breaker, and the second circuit breaker control circuit 30 connects the controller and the second circuit breaker.

[0118] The first circuit breaker control circuit 30 controls the on and off of the first circuit breaker according to the input signal, and the second circuit breaker control circuit 30 controls the on and off of the second circuit breaker according to the input signal. For example, when the first circuit breaker control circuit 30 inputs a high level, the first circuit breaker control circuit 30 controls the first circuit breaker to be turned on; when the first circuit breaker control circuit 30 inputs a low level, the first circuit breaker control circuit 30 controls the first circuit breaker to be turned off, and the control logic of the second circuit breaker control circuit 30 is the same as that of the first circuit breaker control circuit 30. The level signals output by the first circuit breaker control circuit 30 and the second circuit breaker control circuit 30 cannot be the same.

[0119] The bus voltage acquisition circuit includes a voltage sampling resistor and an A / D conversion chip. The bus voltage acquisition circuit inputs the bus voltage signal into the main control chip DSP.

[0120] The control method of the high-power inverter includes:

[0121] The inverter is powered on and the bus capacitor starts to charge;

[0122] After the inverter is powered on normally, the bus capacitor starts to charge. When the bus voltage reaches the minimum operating threshold voltage of the DC / DC switching power supply, the DC / DC switching power supply supplies power to the rectifier main control board and the motor inverter main control board.

[0123] After the rectifier main control board is powered, the voltage signal Vc at both ends of the bus capacitor is obtained;

[0124] The input end of the bus voltage acquisition circuit is connected to the two ends of the bus capacitor. The bus voltage acquisition circuit obtains the bus voltage through the sampling resistor, and converts the analog bus voltage signal into a digital signal through the A / D conversion chip and inputs it into the main control chip DSP.

[0125] When the voltage signal Vc across the bus capacitor is stable, the rectifier main control board controls the second circuit breaker to open and controls the first circuit breaker to close;

[0126] When the inverter is powered on, it is first in a charging state, and the voltage across the bus capacitor keeps changing. When the voltage signal obtained by the main control chip DSP is stable, it indicates that the bus capacitor is fully charged. After the bus is fully charged, the main control chip DSP outputs a low level to the third I / O port to disconnect the second circuit breaker, and simultaneously outputs a high level to the second I / O port to close the first circuit breaker.

[0127] The inverter enters the waiting state.

[0128] The first circuit breaker is closed and the second circuit breaker is opened, so that the charging circuit 20 of the inverter is disconnected, the main circuit 10 is turned on, and the inverter enters the waiting-to-start state.

[0129] The working principle and beneficial effects of this embodiment are as follows: after the rectifier main control board is powered, the main control chip DSP detects the charging status of the bus capacitor, and when the bus voltage reaches stability, the second circuit breaker is automatically disconnected, the first circuit breaker is closed, and the inverter enters the waiting state. This prevents the inverter from being in the charging state for a long time, thereby avoiding the possible three-phase rectification imbalance problem and charging resistor overheating problem caused by IGBT misconduction.

[0130] Example 6, a magnetic levitation centrifuge.

[0131] This embodiment also provides a magnetic levitation centrifuge, which includes the high-power frequency converter described in Example 1. The high-power frequency converter is used to drive the motor and / or magnetic bearing in the magnetic levitation centrifuge, so that the magnetic levitation centrifuge has more reliable performance.

[0132] Embodiment 7, a computer-readable storage medium.

[0133] This embodiment provides a computer storable medium, which stores one or more programs. The one or more programs can be executed by one or more processors to implement the control method of any of the above embodiments.

[0134] The rectifier main control board includes a main control chip DSP, a processor and a memory. The processor is used to execute the control program stored in the memory to implement the control method of any of the above embodiments.

[0135] A storage medium for recording the program code of the software program that can implement the functions of the above-mentioned embodiments is provided in the inverter in the above-mentioned embodiments, and the program code stored in the storage medium is read and executed by the CPU or MPU in the inverter. In this case, the program code read from the storage medium itself executes the functions of the above-mentioned embodiments, and the storage medium storing the program code constitutes an embodiment of the present invention.

[0136] As a storage medium for providing program code, such as a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a magnetic tape or a universal serial bus drive or a combination of two or more of these, in a specific embodiment, the memory includes a read-only memory (ROM); where appropriate, the ROM can be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM) or a flash memory or a combination of two or more of these can be used.

[0137] The functions of the above-described embodiments can be realized not only by executing the read program code by the computer, but also by some or all of actual processing operations performed by an OS (Operating System) running on the computer according to instructions of the program code.

[0138] In addition, an embodiment of the present invention also includes a situation where, after the program code read from the storage medium is written into a function expansion card inserted into the computer, or is written into a memory provided in a function expansion unit connected to the computer, a CPU or the like included in the function expansion card or the function expansion unit performs part of the processing or all of the processing according to the command of the program code, thereby realizing the functions of the above-mentioned embodiments.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A control method for a high-power frequency converter, characterized in that: The frequency converter comprises: Main circuit: connects to the load and supplies power to the load, including rectifier module and bus capacitor; Control circuit: connecting the main circuit and the load, supplying power through the main circuit and controlling the load to start; Charging circuit: connected to the main circuit, used to protect the main circuit when powered on; Voltage collection circuit: connected to the charging circuit and the control circuit, used for collecting the voltage signal Vr of the charging circuit and feeding the voltage signal Vr back to the control circuit, and the control circuit controls the rectifier module according to the voltage signal Vr; The main circuit further comprises a first circuit breaker, and the charging circuit comprises a second circuit breaker and a charging resistor; The control method comprises: Get the voltage value Vr of the charging resistor; When the voltage value Vr of the charging resistor is greater than the preset threshold voltage Vr′, the rectifier main control board sends a pulse to turn off the IGBT modules in sequence; The main rectifier control board sends pulses to turn off the IGBT modules in sequence: When the voltage value Vr of the charging resistor is greater than a preset threshold voltage Vr′, the PWM module is set to an independent mode; After a delay of n seconds, the rectifier main control board sends a pulse to turn off the IGBT modules in sequence; n is 5 seconds, and after waiting for 5 seconds, a pulse is sent to the control end of each IGBT, and the pulse signal has a complete rising edge and a falling edge; The control method further comprises the following steps: Set the PWM module to complementary mode; Start normally; The inverter enters the state of waiting for closing and starting.

2. The control method of a high-power inverter according to claim 1, characterized in that: The frequency converter also includes a bus voltage acquisition circuit, a first circuit breaker control circuit and a second circuit breaker control circuit, the bus voltage acquisition circuit connects the bus and the control circuit, the first circuit breaker control circuit connects the control circuit and the first circuit breaker, and the second circuit breaker control circuit connects the control circuit and the second circuit breaker.

3. The control method of a high-power frequency converter according to claim 1, characterized in that: The control circuit includes a rectifier main control board, a DC-DC power supply and an inverter main control board. The rectifier main control board includes a plurality of IGBT modules and a drive board corresponding to the IGBT modules.

4. The control method of a high-power frequency converter according to claim 1, characterized in that: include: The inverter is powered on, and the bus capacitor starts to charge; The control circuit is powered on and initialized; The main rectifier control board initializes all the IGBT modules simultaneously.

5. The control method of a high-power frequency converter according to claim 4, characterized in that: Also includes: After all the IGBT modules are initialized, all the IGBT modules are stably turned off to ensure the normal operation of the rectifier module; The inverter enters the state of waiting for closing and starting.

6. The control method of a high-power inverter according to claim 1, characterized in that: include: The inverter is powered on, and the bus capacitor starts to charge; The rectifier main control board starts the internal timer after being powered on; When the timing time reaches the preset time t, the rectifier main control board controls the second circuit breaker to open and controls the first circuit breaker to close; The inverter enters the waiting state.

7. The control method of a high-power frequency converter according to claim 1, characterized in that: include: The inverter is powered on, and the bus capacitor starts to charge; The rectifier main control board obtains a voltage signal Vc at both ends of the bus capacitor after being powered; When the voltage signal Vc across the bus capacitor is stable, the rectifier main control board controls the second circuit breaker to open, and at the same time controls the first circuit breaker to close; The inverter enters the waiting state.

8. A magnetic suspension centrifuge, characterized in that: The frequency converter included in the magnetic levitation centrifuge adopts the control method of the high-power frequency converter according to any one of claims 1 to 3.

9. A computer-readable storage medium, characterized in that: The computer storable medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the control method of the high-power inverter according to any one of claims 4 to 7.

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