CN113205942B

CN113205942B - Follow current energy storage demagnetizing device of permanent magnet synchronous motor and implementation method thereof

Info

Publication number: CN113205942B
Application number: CN202110511014.XA
Authority: CN
Inventors: 刘岩山; 张永康
Original assignee: NANJING KINGDOM NEW CONTROL INSTRUMENT CO Ltd
Current assignee: NANJING KINGDOM NEW CONTROL INSTRUMENT CO Ltd
Priority date: 2021-05-11
Filing date: 2021-05-11
Publication date: 2023-11-24
Anticipated expiration: 2041-05-11
Also published as: CN117498732A; CN117353246A; CN113205942A

Abstract

The invention discloses a follow current energy storage degaussing device of a permanent magnet synchronous motor and an implementation method thereof, wherein the follow current energy storage module and a monitoring module which is unified to monitor the degaussing completion condition of the voltage change of an energy storage capacitor are added on the basis of a power driving module of the existing permanent magnet synchronous motor; the follow current energy storage module comprises a MOS tube Q7, a diode VD and an energy storage capacitor C2; the diode VD is connected between the positive electrode of the power supply and a bus for supplying power to the power driving module in a forward direction; the negative electrode of the capacitor C2 is connected with the positive electrode of the power supply VDC, the drain electrode of the MOS tube Q7 is connected with the positive electrode of the capacitor C2, the source electrode is connected with the cathode of the diode VD, and the grid electrode is connected with the singlechip; the single chip microcomputer A/D input is connected with the output of the monitoring module, and the monitoring module directly obtains the sampling voltage change from the two ends of the capacitor C2 or indirectly obtains the voltage from the positive electrode of the capacitor C2 to the negative electrode of the power supply, so that the voltage of the voltage stabilizing tube is stabilized, the influence of the power supply voltage on the sampling precision is reduced, and then the sampling voltage change is obtained.

Description

Follow current energy storage demagnetizing device of permanent magnet synchronous motor and implementation method thereof

Technical Field

The invention relates to the technical field of permanent magnet synchronous motors, in particular to a device for eliminating residual magnetism by stopping and freewheeling energy storage of a permanent magnet synchronous motor with a three-phase stator winding star connection method and an implementation method thereof.

Background

1. Before introducing the background art, the present inventors first describe the basic theory of the characteristics related to the main devices associated with the prior art:

the MOS tube is described as follows:

for a high-power MOS tube, a parasitic diode (body diode) caused by a production process exists between a drain electrode (D) and a source electrode (S) of the MOS tube, and the parasitic diode has the function of: when a large instant reverse current is generated in the circuit, the current can be led out through the diode, so that the MOS tube is not broken down (the MOS tube is protected); when the high-power MOS tube is used for a power bridge arm in a power driving module of the three-phase permanent magnet synchronous motor, a parasitic diode of the high-power MOS tube is completed together with an external diode for freewheeling (when the parasitic diode can completely bear the size of the freewheeling, the external diode for freewheeling can not be added): the motor is switched from the electrified phase to the powered-off phase during normal operation and the powered-off phase is cut off during shutdown, and the generated reverse electromotive force is freewheeling and demagnetized;

the MOS tube is divided into an N channel and a P channel, the positive electrode of the parasitic diode of the NMOS tube is arranged on the source electrode (S), the negative electrode of the parasitic diode of the PMOS tube is arranged on the drain electrode (D), and the negative electrode of the parasitic diode of the PMOS tube is arranged on the source electrode (S); when the NMOS tube and the PMOS tube are used as switches, the current directions are different: when the NMOS tube is used as a switch, the direction of the current ID points from the drain electrode (D) to the source electrode (S); when the PMOS tube is used as a switch, the direction of the current ID points from the source electrode (S) to the drain electrode (D);

The MOS tube is different from the triode and can be reversely conducted; when the control voltage between the MOS tube grid electrode (G) and the source electrode (S) meets the conduction condition, the current ID can flow from the drain electrode (D) to the source electrode (S), and the current ID can also flow from the source electrode (S) to the drain electrode (D), wherein the direction of the current ID depends on the direction of the voltage between the drain electrode (D) and the source electrode (S), and specifically comprises the following steps:

(1) for an NMOS tube: when the direction of the voltage between the drain electrode (D) and the source electrode (S) points to the source electrode (S) and is used as a switch, the direction of the current ID points to the source electrode (S) from the drain electrode (D), and at the moment, the NMOS tube can be conducted only when the control voltage between the grid electrode (G) of the MOS tube and the source electrode (S) meets the conduction condition, otherwise, the NMOS tube is cut off; when the direction of the voltage applied between the drain electrode (D) and the source electrode (S) is directed to the drain electrode (D), the parasitic diode conduction of the NMOS tube directly forms a current ID directed from the source electrode (S) to the drain electrode (D), and a conduction voltage drop of about 0.7V is generated on the parasitic diode, at this time, if the control voltage between the MOS tube grid electrode (G) and the source electrode (S) meets the conduction condition, the NMOS tube is conducted, the conducted parasitic diode is short-circuited, the current ID generated by the conduction of the parasitic diode flows through a conduction channel controlled by the NMOS tube, so that no power consumption is generated on the parasitic diode, and therefore, when the direction of the voltage applied between the drain electrode (D) and the source electrode (S) is directed to the drain electrode (D), the current ID directed from the source electrode (S) to the drain electrode (D) exists regardless of whether the control voltage between the MOS tube grid electrode (G) and the source electrode (S) meets the conduction condition or not;

(2) For PMOS tubes: when the direction of the voltage between the drain electrode (D) and the source electrode (S) points to the drain electrode (D), the switch is used, the direction of the current ID points to the drain electrode (D) from the source electrode (S), and at the moment, the PMOS tube can be conducted only when the control voltage between the grid electrode (G) of the MOS tube and the source electrode (S) meets the conduction condition, otherwise, the PMOS tube is cut off; when the direction of the voltage applied between the drain electrode (D) and the source electrode (S) is directed to the source electrode (S), the parasitic diode conduction of the PMOS tube directly forms a current ID directed to the source electrode (S) from the drain electrode (D), and a conduction voltage drop of about 0.7V is generated on the parasitic diode, at this time, if the control voltage between the MOS tube grid electrode (G) and the source electrode (S) meets the conduction condition, the PMOS tube is conducted, the conducted parasitic diode is short-circuited, and the current ID generated by the conduction of the parasitic diode flows through a conduction path controlled by the PMOS tube, so that no power consumption is generated on the parasitic diode.

As is clear from the analysis in the above (1) and (2), the single-chip high-power MOS transistor cannot be used as a bidirectional switch because a parasitic diode (body diode) is present between the drain (D) and the source (S) of the high-power MOS transistor due to the production process. In order to overcome the technical problem that the parasitic diode affects the use of the MOS transistor as a bidirectional switch, the prior art has been effectively solved, for example, two NMOS transistors are connected back to back, and the source terminals and the gate terminals of the two NMOS transistors are shared. Because the MOS tube is not used as a bidirectional switch in the application, a specific bidirectional switch circuit formed by two NMOS tubes is not elaborated here in detail.

The IGBT tube is described as follows:

the IGBT itself does not have a parasitic diode inside as a MOS transistor, i.e., the IGBT is a device, and does not have a freewheeling diode (a damper diode). The IGBT module is formed by integrating the "igbt+flywheel diode (damper diode)" into one integral unit, so that the flywheel diode (damper diode) in the IGBT module is integrated afterwards. The three poles of the IGBT tube are collector (C), emitter (E) and gate (G), respectively (the gate corresponds to the base of the transistor). The IGBT tube is a compound full-control voltage-driven power electronic device composed of a BJT (bipolar transistor) and a MOS tube, the input stage of the IGBT tube is the MOS tube, and the output stage is the bipolar transistor, so that the IGBT tube can only be used in one direction when being used as a switch in general (conventional);

Aiming at the problem that a conventional IGBT tube can only be unidirectional when used as a switch, a novel bidirectional IGBT power semiconductor device with a five-layer four-section structure is provided, and the novel bidirectional IGBT power semiconductor device is based on a planar grid type IGBT, and the purpose of bidirectional control of the novel device is achieved by adopting a symmetrical mechanism and a two-way input control method for the novel device, so that bidirectional conduction and bidirectional blocking can be realized. Therefore, in the prior art, if the IGBT tube used is bidirectional, it is necessary to specify that the IGBT tube used is a bidirectional IGBT tube.

When the IGBT tube is used for a power bridge arm in a power driving module of the three-phase permanent magnet synchronous motor, the IGBT tube is an IGBT module integrated with a freewheel diode, and the integrated freewheel diode is used for completing the following steps: the motor is switched from the electrified phase to the powered-off phase during normal operation and the powered-off phase is cut off during shutdown, and the generated reverse electromotive force is freewheeling and demagnetized;

2. for a motor driving system (the invention of the same invention and the same date application is filed with the same date application is 2012101639259) for direct main transmission of a loom, which is related to the prior art and has the application number of 2012202368353, the technical scheme is as follows:

the application adds a capacitor CCD for energy storage, a common power switch device QCD for applying high voltage to a three-phase switch reluctance motor winding A, B, C and a power diode VDCD for normally supplying power to the three-phase switch reluctance motor winding A, B, C on the basis of a power converter circuit for driving the three-phase switch reluctance motor in the prior art; the power diode VDCD is connected across a bus for supplying power to a power converter circuit of the three-phase switch reluctance motor driven by the power source VDC in the prior art, the anode of the power diode VDCD and the anode of a filter capacitor CDC of the power source VDC are connected to the bus for supplying power to the power converter circuit; the collector of the power switch device QCD is connected with the positive electrode of the energy storage capacitor CCD, and the emitter of the power switch device QCD is connected with the cathode of the power diode VDCD; the negative electrode of the energy storage capacitor CCD is connected with the positive electrode of the filter capacitor CDC of the power supply VDC; in a power converter circuit for driving a three-phase switched reluctance motor in the prior art, cathodes of power diodes VDAH, VDBH and VDCH are connected to an anode of an energy storage capacitor CCD from a power supply bus. And correspondingly controls the improved power converter circuit for driving the three-phase switch reluctance motor to realize: after the motor is stopped, the reverse electromotive force generated by the motor winding A, B, C charges and stores energy to the energy storage capacitor CCD through the power diodes VDAH, VDBH and VDCH to generate an energy storage voltage VCD; when the motor is started, the power switch device QCD is controlled to be conducted, the power supply VDC is adopted to superpose the energy storage voltage VCD to supply power to the power supply bus, so that larger current passes through the motor winding, the starting torque of the motor is improved, and the requirement of quick starting of the three-phase switch reluctance motor is met; after the motor is started, the power switching device QCD is controlled to be closed, and the power supply VDC supplies power to the power supply bus through the power diode VDCD, so that the motor winding is restored to work under the power supply VDC with normal power supply.

From the figures of this application, the icons of the power switching devices, and the description of the three polarities of the power switching devices in the description thereof, can be unambiguously determined by a person skilled in the art: the 7 power switch devices are IGBT tubes and are not IGBT modules, so that the power switch devices do not have freewheeling diodes (damping diodes). And analyzed, the present inventors considered that a motor drive system for a direct main drive of a loom, having application number 2012202368353, has utility.

3. The background art of the application is explained as follows:

the permanent magnet synchronous motor has the advantages of simple structure, small volume, light weight, small loss, high efficiency, high power factor and the like, and is mainly used for updating and replacing motors of high-performance servo transmission systems and direct current motors, which are required to respond quickly, have wide speed regulation range and are accurate in positioning.

In the case of on-load starting of a permanent magnet synchronous motor, if residual magnetism still exists in a motor winding in the previous shutdown, the starting and the rotating speed tracking of the permanent magnet synchronous motor can be influenced. The existing permanent magnet synchronous motor is powered up, the reverse electromotive force generated in the stator three-phase winding is conducted through a follow current diode (if the switch tube is an MOS tube, a parasitic diode is arranged on the MOS tube, when the parasitic diode is insufficient in power, a diode for follow current is connected in parallel, and the follow current is completed together with the parasitic diode), and then the direct power supply, the power storage and the discharge are carried out, so that demagnetization is carried out, but the elimination condition of residual magnetism is difficult to know, and therefore whether the residual magnetism of the permanent magnet synchronous motor is eliminated to a safe range in the next starting time cannot be determined.

The starting performance of the motor is directly affected by the length of the permanent magnet synchronous motor reaching normal starting torque in the through-current excitation process during starting. The existing method is normal-pressure excitation, excitation is supplied by a power supply, and the power supply voltage is equal to the rated voltage of the synchronous motor. By using the normal-pressure excitation mode, the current cannot rise to the required value of excitation immediately, so that the time for reaching the normal starting torque is long, the starting speed is low, and the starting efficiency of the permanent magnet synchronous motor is not high enough.

Aiming at the problems in the prior art, for a three-phase stator winding star connection permanent magnet synchronous motor, the same applicant applies 3 inventions simultaneously in 2019, 7 and 25 days, and the three-phase stator winding star connection permanent magnet synchronous motor is realized by different setting devices and corresponding methods: during shutdown, the afterflow eliminates remanence and uses a capacitor to boost and store energy; when starting, the high-voltage excitation is carried out by adding the upper voltage of the capacitor to the bus of the motor power driving module at high voltage in a time limit by using a power supply string of the power supply, so that the starting process is shortened, the starting efficiency of the motor is improved, and the power supply of the power supply is used for normally supplying power after the time limit, so that the normal operation of the motor is maintained; the invention has 2 inventions, wherein the monitoring circuit is adopted to monitor the shutdown and eliminate the remanence, so that the adverse effect of excessive remanence on the starting and rotating speed tracking of the motor can be effectively avoided when the motor is started next time. The above 3 inventions are respectively: application number 2019106755101, excitation control device named synchronous motor and use method; application number 2019106755396, namely a device for eliminating remanence by diode freewheeling of a permanent magnet synchronous motor and a using method; application number 2019106755277, named permanent magnet synchronous motor MOS tube afterflow residual magnetism eliminating device and demagnetizing method. And all of the above 3 applications are examined and confirmed by the art to be novel, inventive and practical.

The inventor of the present application has determined that the above 3 technical solutions are all applied to a motor driving system for direct main transmission of a loom according to application number 2012202368353 before the filing date of the present application, and the added technical solution is changed. And through researching the technical schemes of the 3 applications, the following defects and technical problems exist respectively:

the common problem of this is: the technical scheme of the method is realized based on that no parasitic diode exists in the MOS tube, otherwise, the shutdown energy storage and demagnetization method cannot be reproduced in the application numbers 2019106755101 and 2019106755277, and the more effective shutdown energy storage and demagnetization method exists in the device of the application number 2019106755396 after the diodes VD1, VD2 and VD3 are removed (not needed); and unambiguously, the prior art driving module is well known to those skilled in the art that the MOS transistor is a high-power MOS transistor: for application numbers 2019106755101 and 2019106755277, the MOS transistor Q1 (MOS transistor T1), the MOS transistor Q2 (MOS transistor T2), the MOS transistor Q3 (MOS transistor T3), the MOS transistor Q4 (MOS transistor T4), the MOS transistor Q5 (MOS transistor T5) and the MOS transistor Q6 (MOS transistor T6) can effectively maintain the normal operation of the synchronous motor due to the freewheeling effect of the parasitic diode; for application number 2019106755396, the diode VD2 for freewheeling is connected to the MOS transistor Q6, so that the driving module of the motor can effectively maintain the normal operation of the synchronous motor only if parasitic diodes play a role in freewheeling in the MOS transistors Q1, Q2, Q3, Q4 and Q5, but, although the diode VD1 corresponds to corresponding freewheeling for the turn-off of the MOS transistor Q4, the diode VD3 corresponds to corresponding freewheeling for the turn-off of the MOS transistor Q2, and the freewheels of the diode VD1 and the diode VD3 are charged into the high-order energy storage capacitor C2 and cannot perform freewheeling through the upper tube conduction phase of the bridge arm, thereby not rapidly releasing the reverse electromotive force and demagnetizing, so that the motor can effectively maintain the normal operation of the synchronous motor only if parasitic diodes (or freewheeling diodes connected at two ends of the MOS transistor) are connected through the upper tube conduction phase of the bridge arm.

Secondly, to the excitation control device with the application number of 2019106755101 and the name of synchronous motor and the using method, the following analysis is carried out:

in the device, in a driving module of a permanent magnet synchronous motor adopting an MOS tube as a power tube of a three-phase stator winding star connection method in the prior art, the scheme setting is carried out by identifying that parasitic diodes do not exist in MOS tubes (T1, T2, T3, T4, T5 and T6), and additionally arranging the MOS tubes (T7, T8, T9 and T10) in the driving module; the device scheme is specifically as follows: the drain electrode (D) of the MOS tube T8 is connected with the central point of the star connection of the three-phase stator winding, and the source electrode (S) is connected with the negative electrode of a power supply (VDC 1) for supplying power to the driving module in the prior art; disconnecting the positive electrode of the power supply (VDC 1) from a power supply bus of a driving module in the prior art, adding a diode VD1, connecting the positive electrode of the power supply (VDC 1) and the power supply bus of the driving module in the prior art in series, connecting the positive electrode of the diode VD1 with the positive electrode of the power supply (VDC 1), and connecting the negative electrode of the diode VD1 to the power supply bus of the driving module in the prior art; the energy storage capacitor C2 is additionally arranged, the negative electrode of the capacitor C2 is connected with the positive electrode of the power supply (VDC 1), and the positive electrode of the capacitor C2 is connected with the drain electrode (D) of the additionally arranged MOS tube T7, the source electrode (S) of the MOS tube T9 and the source electrode (S) of the MOS tube T10; the power supply VDC2 is additionally arranged, the positive electrode of the power supply VDC2 is connected with the drain electrode (D) of the MOS tube T10, and the negative electrode of the power supply VDC1 is connected with the positive electrode of the power supply; the source electrode (S) of the MOS tube T7 is connected to a power supply bus of a driving module in the prior art; the diode VD2 is additionally arranged, the anode of the diode is connected to a power supply bus of a driving module in the prior art, and the cathode of the diode is connected with the drain electrode (D) of the MOS tube T9;

The MOS tube T8 is matched with the MOS tube T9 and the diode VD2, and is used for storing energy and demagnetizing reverse electromotive force in three phases of the motor to the capacitor C2 after the motor is stopped;

if the energy storage of the capacitor C2 does not meet the requirement, the MOS tube T10 is controlled to be conducted, and the power supply VDC2 supplements the energy storage to the capacitor C2, so that the technical scheme is not in the range of the application, and the power supply VDC2 does not supplement the energy storage scheme to the capacitor C2 for analysis;

the added MOS tube T8 is matched with the added MOS tube T7, and is used for switching on and switching off at a limited time when the motor is started, the starting voltage is increased for the motor by adopting energy storage on a power supply (VDC 1) serial capacitor C2, and all upper arm MOS tubes in a bridge arm are controlled to be conducted to correspond to the communication flow, and the method is said to realize the sequential excitation of three phases of the motor, shorten the starting process of the synchronous motor and improve the starting efficiency of the synchronous motor;

after the motor is started, the MOS tube T7 is closed, a power supply (VDC 1) supplies power to the driving module through the diode VD1, and the motor can be said to normally operate, and the motor can not normally operate in practice, because a parasitic diode cannot be arranged in the MOS tube of the application, otherwise, the shutdown energy storage and demagnetization method is not established;

the application is specifically analyzed as follows:

(1) Since parasitic diodes are actually present in the MOS transistor, the parasitic diodes are caused by the production process; so that when the machine is stopped: when the A phase is the reverse electromotive force generated by the turn-off of the MOS tube T4 of the corresponding bridge arm lower tube, the parasitic diode in the MOS tube T1 of the corresponding bridge arm upper tube is connected with the flywheel, and then the parasitic diode in the MOS tube T7 is connected with the flywheel to charge the energy storage capacitor C2; when the B phase is the reverse electromotive force generated by the turn-off of the MOS tube T6 of the corresponding bridge arm lower tube, the parasitic diode in the MOS tube T3 of the corresponding bridge arm upper tube is connected with the flywheel, and then the parasitic diode in the MOS tube T7 is connected with the flywheel to charge the energy storage capacitor C2; when the C phase is the reverse electromotive force generated by the turn-off of the MOS tube T2 of the corresponding bridge arm lower tube, the parasitic diode in the MOS tube T5 of the corresponding bridge arm is connected with the flywheel, and then the parasitic diode in the MOS tube T7 is connected with the flywheel to charge the energy storage capacitor C2; as is well known to those skilled in the art: all the three bridge arms are not stopped when the corresponding phase is electrified after the lower pipe is conducted, but all the bridge arms are stopped when the upper pipe is conducted and all the bridge arms are stopped when the lower pipe is conducted, so that during stopping, the reverse electromotive force generated by the corresponding phase of the lower pipe is actually added with the reverse electromotive force generated by the corresponding phase of the upper pipe in series, the parasitic diode in the upper pipe is in continuous flow when the lower pipe is conducted by the bridge arms, the parasitic diode in the MOS pipe T7 is used for charging the energy storage capacitor C2, and the parasitic diode in continuous flow when the upper pipe is conducted by the bridge arms is used for forming a release and charging path after the capacitor C1 and the VDC; and (3) injection: the analysis after shutdown is naturally realized under the condition of not controlling the MOS tube;

(2) Under the condition that no parasitic diode exists in the MOS tube, the using method of the corresponding device is analyzed:

in the second step of the method for using the corresponding device, it is described that "when the synchronous motor needs to be excited and started: the single chip microcomputer controls the MOS tube T1, the MOS tube T3 and the MOS tube T5 to be conducted, the single chip microcomputer controls the MOS tube T2, the MOS tube T4, the MOS tube T6, the MOS tube T8, the MOS tube T9 and the MOS tube T10 to be in a cut-off state all the time, meanwhile, the single chip microcomputer controls the MOS tube T7 to be cut-off after being conducted for 1 s-2 s, energy in the capacitor C2 is used in electric excitation, and after the excitation is finished, the motor has a starting condition; because the MOS transistor T8 is in the off state, the magnetic field cannot be formed by the through-flow in the three phases, and in the next step, even if the MOS transistor T8 is controlled to be turned on, the magnetic field formed by the through-flow in the three phases is a fixed magnetic field instead of a rotating magnetic field, and at this time, the fixed magnetic field is not the rotating magnetic field required for starting at all, but the effect is also called that the effect is that the voltage is applied to the two ends of the motor winding by using the voltage higher than the normal driving voltage, so that the sequential excitation of the three phases of the motor is realized, and the person skilled in the art does not know what the above effect is.

The second step of the method for using the corresponding device is described as "when the synchronous motor is stopped: the single chip microcomputer controls the MOS tube T8 and the MOS tube T9 to be conducted, the MOS tube T1 is controlled to be conducted for 0.3s to 0.6s, the MOS tube T3 is controlled to be conducted for 0.3s to 0.6s, the MOS tube T5 is controlled to be conducted for 0.3s to 0.6s, the single chip microcomputer controls the MOS tube T2, the MOS tube T4, the MOS tube T6, the MOS tube T7 and the MOS tube T10 to be in a cut-off state all the time, and when residual energy feedback is completed, the single chip microcomputer controls the MOS tube T8 and the MOS tube T9 to be cut-off. ", the problem comes:

Assuming that all three phases are reverse electromotive forces generated by turning off and stopping when the corresponding bridge arm lower pipe is turned on, conducting the corresponding bridge arm upper pipe for releasing and controlling the reverse electromotive forces on the corresponding phases, wherein the time is set to be 0.3 s-0.6 s: if the time is within 0.3S-0.6S, the release is completed without finishing the reverse electromotive force, and as the power VDC1 acts on the drain electrode (D) of the MOS tube through the diode VD1, the MOS tube conducted by the bridge arm is in the residual time, the power VDC1 is enabled to flow towards the released reverse electromotive force because the direction of the voltage between the drain electrode (D) and the source electrode (S) is directed towards the drain electrode (D), so that the set conduction time is overlong, the conduction current is generated in the residual time after the complete release, if the set conduction time is reduced, the time is reduced, and after the MOS tube is turned off, the reverse electromotive force in the release phase is not released, namely the residual magnetism does not reach the safety range, and therefore, the application adopts the timing control to release the corresponding MOS tube to conduct after the shutdown; the application adopts the control of the MOS tube T1 to be conducted for 0.3 s-0.6 s, the MOS tube T3 to be conducted for 0.3 s-0.6 s and the MOS tube T5 to be conducted for 0.3 s-0.6 s in sequence, the time of release and demagnetization is integrally prolonged after shutdown, and the quick effect cannot be achieved;

Because the actual three phases cannot be all the reverse electromotive forces generated by shutdown when the corresponding bridge arm lower pipe is turned on, the three phases are certain to exist, the corresponding phases of the reverse electromotive forces generated by shutdown when the bridge arm upper pipe is turned on are not only impossible to release the reverse electromotive forces in the phases when the bridge arm upper pipe is turned on again, but also the power supply VDC1 generates impact current in the phases after overlapping the reverse electromotive forces, so that the conducting MOS pipe is damaged.

(3) Because the MOS tube adopted in the three-phase driving module of the permanent magnet synchronous motor in the prior art is a high-power MOS tube, and the parasitic diode exists in the MOS tube actually, the application is analyzed according to the using method of the corresponding device under the condition that the parasitic diode exists in the MOS tube:

Because the parasitic diode exists in the MOS tube T7, after the shutdown, the control of the conduction of the MOS tube T9 has no effect, because the freewheeling on the bus is charged to the energy storage capacitor C2 through the parasitic diode freewheeling in the MOS tube T7 at the moment; assuming that no parasitic diode exists in the MOS tube T7, after the power is stopped, the freewheeling on the bus is charged to the energy storage capacitor C2 through the diode VD2 and the parasitic diode freewheeling in the MOS tube T9, the control of the MOS tube T9 is conducted, the parasitic diode conducted on the MOS tube is only short-circuited, and the freewheeling generated by the conduction of the parasitic diode flows through a conduction channel controlled by the MOS tube, so that no power consumption is generated on the parasitic diode;

the control of the MOS tube T1, the MOS tube T3 and the MOS tube T5 is conducted, and the parasitic diode conducted on the MOS tube is only short-circuited, so that the follow current generated by the conduction of the parasitic diode flows through a conduction path controlled by the MOS tube, and the parasitic diode does not generate power consumption; the control conduction of the MOS tube T8 is that the parasitic diode which is conducted on the MOS tube T8 is only short-circuited, so that the follow current generated by the conduction of the parasitic diode flows through a conduction path controlled by the MOS tube T8, and the parasitic diode does not generate power consumption;

Because parasitic diodes in the MOS tube play a role of follow current, the MOS tube T1, the MOS tube T3, the MOS tube T5 and the MOS tube T3 which are sequentially controlled by the parasitic diodes are conducted for 0.3s to 0.6s, the MOS tube T3 is conducted for 0.3s to 0.6s, and the MOS tube T3 and the MOS tube T5 which are conducted can generate the problem that power supplies are conducted to corresponding communication flows;

therefore: due to the existence of parasitic diodes in the MOS tube: after stopping, controlling the conduction of the MOS tube, namely shorting the parasitic diode which is conducted by the corresponding MOS tube, so that the follow current generated by the conduction of the parasitic diode flows through a conduction path controlled by the MOS tube, and no power consumption is generated on the parasitic diode; when the reverse electromotive force is not released, the turned-on MOS tube is controlled to be turned off, so that the reverse electromotive force can not be turned off to continue the release process, and the parasitic diode in the MOS tube can continue to freewheel; after the machine is stopped, the MOS tube is not controlled to be conducted, reverse electromotive force is naturally released through a parasitic diode in the MOS tube as well as energy storage and demagnetization are carried out, so that the MOS tube T1, the MOS tube T3 and the MOS tube T5 which are sequentially controlled are conducted at fixed time, and the problem that power supply flows to corresponding communication can occur in all-in-all manner;

if parasitic diodes existing in the MOS tube are not considered to play a role of follow current, the single-chip microcomputer is stopped once power is lost, reverse electromotive force in three phases cannot be released, and energy storage and demagnetization cannot be performed.

The following analysis is performed on a device and a demagnetizing method for eliminating remanence through the MOS tube freewheeling of the permanent magnet synchronous motor with the application number of 2019106755277:

in the device, in a driving module of a permanent magnet synchronous motor adopting an MOS tube as a power tube in a star connection method of a three-phase stator winding in the prior art, the scheme is set by adopting that parasitic diodes do not exist in MOS tubes (Q1, Q2, Q3, Q4, Q5 and Q6) of the driving module, and the additionally arranged MOS tubes (Q7 and Q8) of the driving module are also adopted as the parasitic diodes; the device scheme is specifically as follows:

disconnecting the positive electrode of the power supply (VDC 1) from a power supply bus of a driving module in the prior art, adding a diode VD1, connecting the positive electrode of the power supply (VDC) and the power supply bus of the driving module in the prior art in series, connecting the positive electrode of the diode VD1 with the positive electrode of the power supply (VDC), and connecting the negative electrode of the diode VD1 to the power supply bus of the driving module in the prior art; the energy storage capacitor C2 is additionally arranged, the negative electrode of the capacitor C2 is connected with the positive electrode of the power supply (VDC), and the positive electrode of the capacitor C2 is connected with the drain electrode (D) of the additionally-arranged MOS tube Q7; the source electrode (S) of the MOS tube Q7 is connected to a power supply bus of a driving module in the prior art; connecting the drain electrode (D) of the added MOS tube Q8 with the central point of the star connection of the three-phase stator winding; the resistor R1, the diode VD2 and the amplifying circuit are additionally arranged, the cathode of the diode VD2 is connected with the source electrode (S) of the MOS tube Q8, the anode of the diode VD2 is connected with the cathode of the power supply (VDC) after being connected with the resistor R1 in series, and leads are led to the input end of the amplifying circuit from the connection line of the anode of the diode VD2 and the resistor R1; adding a voltage dividing circuit from the positive electrode of the capacitor C2 to the negative electrode of a power supply (VDC);

Wherein:

the voltage dividing circuit is used for judging whether demagnetization is finished or not through the change rate of the sampling voltage of the positive electrode of the current collecting capacitor C2 to the ground after shutdown when a power supply (VDC) is smaller than or equal to 48V;

the resistor R1 and the amplifying circuit are used for judging whether demagnetization is finished or not by calculating the magnitude of sampling current through the collector voltage of the resistor R1 after stopping when a power supply (VDC) is larger than 48V;

the added MOS tube Q7 is matched with the added MOS tube Q8, and is used for storing energy and demagnetizing reverse electromotive force in three phases of the motor to the capacitor C2 after the motor is stopped;

the MOS tube Q7 is additionally arranged and is also used for switching on and switching off at a limited time when the motor is started, and the starting voltage is increased for the motor by adopting energy storage on a power supply (VDC) serial capacitor C2;

after the motor is started, the MOS tube Q7 is closed, a power supply (VDC) supplies power to the driving module through the diode VD1, and the motor runs normally;

in practice, the motor in the application cannot operate effectively, because the parasitic diode must not exist in the MOS tube of the application, otherwise, the shutdown energy storage and degaussing methods are not established;

The application is specifically analyzed as follows:

because this application is equivalent to in order to overcome application number 2019106755101, in excitation controlling means and the method of use that the name is synchronous motor, when the corresponding looks reverse electromotive force is released to the upper tube conduction of control bridge arm in proper order timing after the power failure machine, the unreliable problem that exists to after stopping the motor, adopt the last MOS pipe of control corresponding bridge arm in proper order in real time to switch on, make the reverse electromotive force that produces on the corresponding looks, through the MOS pipe freewheel that its switched on charges to energy storage capacitor C2 through the MOS pipe Q7 that the control switched on:

when the voltage of the power supply VDC is larger than 48V, the current of the reverse electromotive force release phase is monitored to be smaller than or equal to a first preset value in real time, the release and demagnetization of the reverse electromotive force release phase are considered to be completed, the MOS tube which is correspondingly conducted in the release is turned off, the upper MOS tube of the next corresponding bridge arm is controlled to be conducted, the reverse electromotive force generated on the phase is enabled to be charged into the energy storage capacitor C2 through the MOS tube which is conducted through the follow current of the MOS tube which is conducted, when the current of the reverse electromotive force release phase is monitored to be smaller than or equal to the first preset value in real time, the release and demagnetization of the reverse electromotive force release phase are considered to be completed, the MOS tube which is correspondingly conducted is turned off, so that the operation is analogized in turn, and the MOS tube Q7 and the MOS tube Q8 which are conducted are turned off after the release of the 3 phases is completed, namely the complete elimination of the residual magnetism is considered to be judged;

When the voltage of the power supply VDC is smaller than or equal to 48V, charging of the opposite-phase electromotive force releasing relative capacitor C2 is monitored in real time, when the change rate of the capacitor C2 to the ground is smaller than a second preset value, releasing and demagnetizing of the opposite-phase electromotive force releasing phase are considered to be completed, the MOS tube which is correspondingly conducted after releasing is turned off, the upper MOS tube of the corresponding bridge arm is controlled to be conducted, the opposite-phase electromotive force generated on the phase is enabled to be charged to the energy storage capacitor C2 through the MOS tube which is conducted after the MOS tube which is conducted continuously, charging of the capacitor C2 is monitored to be conducted in real time, when the change rate of the capacitor C2 to the ground is smaller than the second preset value, releasing and demagnetizing of the opposite-phase electromotive force releasing phase are considered to be completed, and then the MOS tube which is correspondingly conducted is turned off, so that after releasing in 3 phases is completed, the MOS tube Q7 and the MOS tube Q8 which is conducted are turned off are judged to be completed, and the whole residual magnetism elimination is considered to be completed;

in fact, as parasitic diodes in the MOS tube play a role of follow current, the parasitic diodes sequentially monitor the release current or the charging voltage in real time, the MOS tube Q1, the MOS tube Q3 and the MOS tube Q5 are controlled to be turned on or turned off, the MOS tube Q3 and the MOS tube Q5 after being turned on can generate the problem that the power supply flows to the corresponding communication, because the parasitic diodes can only be turned on and then monitored, whether the turned-on MOS tube Q3 and the turned-off MOS tube Q5 are turned off is determined according to the monitoring result;

After the MOS transistor Q1, the MOS transistor Q3 and the MOS transistor Q5 are controlled to be conducted, once an error occurs in monitoring, the upper MOS transistor of the conducted bridge arm is turned off later, and the problem that a corresponding phase generates power supply to a corresponding communication flow can also occur; therefore, after motor stopping is applied, the upper MOS tubes of the corresponding bridge arms are sequentially controlled to be conducted in real time, so that the reverse electromotive force generated on the corresponding phase is charged to the energy storage capacitor C2 through the MOS tube which is conducted through the upper MOS tube, and besides the problem that the time for releasing and demagnetizing is integrally prolonged after stopping is solved, the unreliable problem existing when the upper MOS tube of the corresponding bridge arm is controlled to be conducted and the corresponding reverse electromotive force is released is not solved;

regarding the application, it is proposed that: when the voltage of the dc power source VDC is greater than 48V, if the method of sampling the voltage is adopted, the amplitude variation of the sampled voltage is not obvious relative to the voltage of the dc power source VDC, which ultimately results in insufficient judgment accuracy, so in this application, only when the voltage of the dc power source VDC is less than or equal to 48V, the method of sampling the voltage is adopted; when the voltage of the direct current power source VDC is less than or equal to 48V, if a method of sampling current is adopted, the judgment accuracy is insufficient due to the small sampling current, so in the application, only when the voltage of the direct current power source VDC is greater than 48V, the method of sampling current is adopted; however, as is well known in the art, during the shutdown freewheeling process, once the current in the freewheeling circuit is equal to zero or the voltage on the capacitor for charging and storing energy remains unchanged, the freewheeling is completely ended; the inventors therefore consider that: the root cause of the method that the completion condition of monitoring and eliminating residual magnetism can not be effectively unified into sampling voltage is as follows: the influence of the power supply voltage on the sampling voltage dividing circuit cannot be eliminated, so that when the voltage of the direct-current power supply VDC is larger than 48V, the singlechip cannot effectively acquire the voltage change on the energy storage capacitor; the root cause of the method that the completion condition of monitoring and eliminating residual magnetism can not be effectively unified into sampling current is as follows: the resistance of the current sampling resistor cannot be large, the resistance is large, the effective energy storage of the follow current is affected, the high current (which is called as the application number) generated by stopping the follow current when the voltage of the direct current power supply VDC is larger than 48V is also generated on the sampling resistor, the single chip microcomputer cannot effectively acquire the voltage change of the high current on the sampling resistor, but the resistance is large, the low current generated by stopping the follow current when the voltage of the direct current power supply VDC is smaller than or equal to 48V is generated in the application number, and the voltage generated on the sampling resistor can effectively acquire the voltage change of the low current on the sampling resistor; and the inventors also considered that: when the current of the follow current loop is obtained by adopting a current sampling method, namely a sampling resistor, the obtained current is zero or tends to zero, and stopping and eliminating residual magnetism are determined to be completed;

Other problems also existing in the application are the same as those of the excitation control device and the using method of the synchronous motor with the application number 2019106755101, and are not described. If parasitic diodes existing in the MOS tube are not considered to play a role of follow current, the single-chip microcomputer is stopped once power is lost, reverse electromotive force in three phases cannot be released, and energy storage and demagnetization cannot be performed.

For the application number 2019106755396, the diode freewheel residual magnetism eliminating device for the permanent magnet synchronous motor and the using method thereof are specifically analyzed as follows:

the application is equivalent to solving the problems that in the application numbers 2019106755101 and 2019106755277, the power failure after-control MOS tube is conducted to release the reverse electromotive force, the release time is unreliable and integrally prolonged, and the reverse electromotive force in three phases cannot be released once the singlechip is stopped when the power is lost; in the device of the application, in a driving module taking MOS tubes as power tubes of a permanent magnet synchronous motor adopting a three-phase stator winding star connection method in the prior art, the scheme setting is carried out by adopting diodes for free parasitic diodes in the MOS tubes (Q1, Q2, Q3, Q4, Q5 and Q6) and the additionally arranged MOS tube Q7 is also regarded as free parasitic diodes; the device scheme is specifically as follows:

Disconnecting the positive electrode of the power supply (VDC) from a power supply bus of a driving module in the prior art, adding a diode VD4, connecting the positive electrode of the power supply (VDC) and the power supply bus of the driving module in the prior art in series, connecting the positive electrode of the diode VD4 with the positive electrode of the power supply (VDC), and connecting the negative electrode of the diode VD4 to the power supply bus of the driving module in the prior art; the energy storage capacitor C2 is additionally arranged, the negative electrode of the capacitor C2 is connected with the positive electrode of the power supply (VDC), and the positive electrode of the capacitor C2 is connected with the drain electrode (D) of the additionally-arranged MOS tube Q7; the source electrode (S) of the MOS tube Q7 is connected to a power supply bus of a driving module in the prior art; and a diode VD1, a diode VD2 and a diode VD3 are additionally arranged; the anode of the diode VD1 is connected with the source electrode (S) of the MOS tube Q1, and the cathode is connected with the anode of the capacitor C2; the anode of the diode VD3 is connected with the source electrode (S) of the MOS tube Q5, and the cathode is connected with the anode of the capacitor C2; the anode of the diode VD2 is connected with the source electrode (S) of the MOS tube Q6, and the cathode is connected with the drain electrode (D) of the MOS tube Q6; through analysis, the circuit can only be used in a driving module in the prior art, when the MOS transistor Q4, the MOS transistor Q2 and the MOS transistor Q3 are electrified and conducted, the circuit is stopped, reverse electromotive forces generated by the A phase, the B phase and the C phase can charge and demagnetize the capacitor C2 through the added diode VD1, the diode VD2 and the diode VD3, and the circuit is stopped in other electrified states, or part of the reverse electromotive forces are not established or all of the reverse electromotive forces are not established;

In order to be able to monitor whether the degaussing is completed after the shutdown, two schemes are adopted in this application:

the first is, when the power (VDC) is less than or equal to 48V, adopt and add the bleeder circuit from positive pole of the capacitor C2 to negative pole of the power (VDC); after the machine is stopped, judging whether the demagnetization is finished or not by adopting the change rate of the sampling voltage of the positive electrode of the collector capacitor C2 to the ground;

secondly, when the power supply (VDC) is larger than 48V, an additional resistor R1 and an amplifying circuit are adopted, the additional resistor R1 is connected in series in a branch circuit of a diode VD2 which is additionally connected on a MOS tube Q6 in parallel and is used for follow current, namely, after the anode of the diode VD2 is connected with the resistor R1 in series, the diode is connected with a source electrode (S) of the MOS tube Q6, and a lead is led to the input end of the amplifying circuit from the connecting line of the anode of the diode VD2 and the resistor R1; after the machine is stopped, the magnitude of sampling current is calculated through the resistor R1 sampling voltage, so as to judge whether demagnetization is finished or not.

The MOS tube Q7 is additionally arranged, is used for switching on and switching off at a limited time when the motor is started, increases the starting voltage for the motor by adopting the energy storage on the power supply (VDC) serial-plus capacitor C2, and sequentially excites three phases of the motor by the driving module, so that the starting process of the synchronous motor is shortened, and the starting efficiency of the synchronous motor is improved;

After the MOS tube Q7 is closed in a time limit, a power supply (VDC) supplies power to the driving module through the diode VD4, and the motor runs normally;

in practice, the motor in the application cannot operate effectively, because the parasitic diode cannot be arranged in the MOS tube of the application, otherwise, the using method is not established (for example, when the voltage of the direct-current power supply VDC is greater than 48V, the method for sampling current adopted by the direct-current power supply VDC is not established);

Because the MOS tube in the driving module is set to have no parasitic diode, the motor can not normally operate in practice, and the MOS tube is equivalent to the parasitic diode in the driving module after the MOS tube is connected with the current diode in parallel.

By the above analysis of the technical solutions of application numbers 2019106755101, 2019106755396 and 2019106755277, it is determined with certainty that:

the technical schemes of the invention of the 3 same-day application are not practical, so that the technical schemes can not be effectively reproduced, and the motor can not normally operate;

the technical solution of the 3 same-day applications simultaneously teaches the person skilled in the art in reverse: under the condition of keeping the power module of the permanent magnet synchronous motor driving the three-phase stator winding star connection method in the prior art unchanged before the application date, the power module is turned over by using the shutdown energy storage technical scheme additionally arranged in application number 2012202368353, and shutdown, boosting, energy storage and degaussing cannot be realized.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a follow current energy storage demagnetizing device of a permanent magnet synchronous motor and an implementation method thereof under the condition that a power driving module of the permanent magnet synchronous motor with a three-phase stator winding star connection method in the prior art and a control method of the power driving module are unchanged, wherein the follow current energy storage demagnetizing device is implemented during shutdown: the follow current effectively boosts the energy storage and eliminates the remanence; the monitoring of the completion condition of eliminating residual magnetism under different conditions of power supply voltage is unified into an effective monitoring.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

a follow current energy storage degaussing device of a permanent magnet synchronous motor is characterized in that a follow current energy storage module and a monitoring module which is unified to monitor degaussing completion conditions of capacitor voltage change of energy storage are additionally arranged on the basis of a power driving module of the permanent magnet synchronous motor based on a three-phase stator winding star connection method; the follow current energy storage module comprises a MOS tube Q7, a diode VD and an energy storage capacitor C2; disconnecting the positive electrode of the power supply VDC from a bus for supplying power to the power driving module, connecting the positive electrode of the power supply VDC in series with the diode VD, and then connecting the positive electrode of the power supply VDC to the bus for supplying power to the power driving module; the cathode of the capacitor C2 is connected with the anode of the power supply VDC, the anode of the capacitor C2 is connected with the drain electrode of the MOS tube Q7, the source electrode of the MOS tube Q7 is connected with the cathode of the diode VD, and the grid electrode of the MOS tube Q7 is connected with the output of the singlechip; the A/D input of the singlechip is connected with the output of the monitoring module, and the voltage change of the capacitor C2 is directly sampled from the two ends of the capacitor C2 through the monitoring module, or the voltage is indirectly obtained from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, so that the voltage of the voltage stabilizing tube is stabilized, the influence of the voltage of the power supply VDC on the sampling precision is reduced, and then the voltage change of the capacitor C2 is sampled.

The MOS transistor Q7 is an NMOS transistor with a parasitic diode.

The monitoring module comprises a voltage stabilizing tube DZ1, a switching tube T2, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5; the voltage regulator is used for obtaining voltage from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, and indirectly sampling after the voltage disturbance of the power supply VDC is filtered out through voltage stabilization of the voltage regulator tube DZ 1; the cathode of the voltage stabilizing tube DZ1 is connected with the positive electrode of the capacitor C2, the anode of the voltage stabilizing tube DZ1 is connected with the high potential end of the switch tube T1, the low potential end of the switch tube T1 is connected with the negative electrode of the power supply VDC after being connected with the resistor R1 and the resistor R2 in series, the connection position of the resistor R1 and the resistor R2 is connected with the A/D input of the singlechip through a lead wire, the control end of the switch tube T1 is connected with the high potential end of the switch tube T2 after being connected with the high potential end of the switch tube T2 in series, the low potential end of the switch tube T2 is connected with the negative electrode of the power supply VDC, the control end of the switch tube T2 is respectively connected with one end of the resistor R4 and one end of the resistor R5, the other end of the resistor R4 is connected with the negative electrode of the power supply VDC, and the other end of the resistor R5 is connected with the output of the singlechip I/O.

The above-mentioned voltage stabilizing value selection of the voltage stabilizing tube DZ1 should satisfy: the voltage of the power supply VDC minus the voltage stabilizing value of the voltage stabilizing tube DZ1 is larger than zero and smaller than or equal to 48V; the regulated value of the regulator tube DZ1 is preferably 10V smaller than the voltage of the power supply VDC.

The monitoring module further comprises a voltage stabilizing tube DZ2, a switching tube T3, a photoelectric coupler U1, a resistor R6, a resistor R7, a resistor R8, a resistor R9 and a resistor R10; the voltage regulator is used for obtaining voltage from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, and indirectly sampling after the voltage disturbance of the power supply VDC is filtered out through voltage stabilization of the voltage regulator tube DZ 2; the cathode of the voltage stabilizing tube DZ2 is connected with the positive electrode of the capacitor C2, the anode of the voltage stabilizing tube DZ2 is connected with the collector of a phototriode in the photoelectric coupler U1, the emitter of the phototriode in the photoelectric coupler U1 is sequentially connected with a resistor R6 and a resistor R7 in series and then is connected with the negative electrode of a power supply VDC, the lead wire at the joint of the resistor R6 and the resistor R7 is connected with the A/D input of the singlechip, the anode of the light emitting diode in the photoelectric coupler U1 is connected with the power supply of the singlechip after being connected with a resistor R8 in series, the cathode of the light emitting diode in the photoelectric coupler U1 is connected with the high potential end of a switching tube T3, the low potential end of the switching tube T3 is connected with the negative electrode of the power supply VDC, the control end of the switching tube T3 is respectively connected with one end of a resistor R9 and one end of a resistor R10, the other end of the resistor R9 is connected with the negative electrode of the power supply VDC, and the other end of the resistor R10 is connected with the output of the singlechip I/O.

The photoelectric coupler U1 is a digital photoelectric coupler, when the light emitting diode in the photoelectric coupler U1 is electrified, the phototriode in the photoelectric coupler U1 is saturated and conducted, and when the light emitting diode in the photoelectric coupler U1 is not electrified, the phototriode in the photoelectric coupler U1 is cut off.

The above-mentioned voltage stabilizing value selection of the voltage stabilizing tube DZ2 should satisfy: the voltage of the power supply VDC minus the voltage stabilizing value of the voltage stabilizing tube DZ2 is larger than zero and smaller than or equal to 48V; the regulated value of the regulator tube DZ2 is preferably 2V smaller than the voltage of the power supply VDC.

The monitoring module further comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a photoelectric coupler U2, a photoelectric coupler U3 and a switch tube T4; the capacitor C2 is used for directly acquiring voltages from two ends of the capacitor C2 to carry out sampling; the anode of the light emitting diode in the photoelectric coupler U2 is connected with the positive electrode of the capacitor C2 after being connected with the resistor R11 in series, the cathode of the light emitting diode in the photoelectric coupler U2 is connected with the collector of the phototriode in the photoelectric coupler U3, the emitter of the phototriode in the photoelectric coupler U3 is connected with the negative electrode of the capacitor C2, the anode of the light emitting diode in the photoelectric coupler U3 is connected with the resistor R13 in series and then is connected with the power supply of the singlechip, the cathode of the light emitting diode in the photoelectric coupler U3 is connected with the high-potential end of the switch tube T4, the low-potential end of the switch tube T4 is connected with the negative electrode of the power supply VDC, the control end of the switch tube T4 is respectively connected with one end of the resistor R14 and one end of the resistor R15, the other end of the resistor R14 is connected with the negative electrode of the power supply VDC, the other end of the resistor R15 is connected with the output of the singlechip I/O, the collector of the phototriode in the photoelectric coupler U2 is connected with the singlechip after being connected with the resistor R12 in series, the emitter of the phototriode in the photoelectric coupler U2 is connected with the negative electrode of the singlechip, and then is connected with the negative electrode of the phototriode in series resistor R16 of the singlechip.

The photoelectric coupler U3 is a digital photoelectric coupler.

The photo coupler U2 is a linear photo coupler.

In order to achieve the above object, another aspect of the present invention

A realization method of a follow current energy storage demagnetizing device of a permanent magnet synchronous motor comprises the following steps:

the method comprises the steps that voltage changes of a monitoring capacitor C2 are uniformly adopted for different power supply VDC voltages, and the voltage changes of the capacitor C2 are directly sampled from two ends of the capacitor C2 or indirectly obtained from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC through a monitoring module as conditions for judging whether demagnetization is finished, so that voltage regulation of a voltage regulator tube reduces the influence of the power supply VDC voltage on sampling precision, and then the voltage changes of the capacitor C2 are sampled;

and (3) when the machine is stopped:

the singlechip outputs a conduction control signal to the grid electrode of the MOS transistor Q7, the power driving module uses a freewheeling diode to freewheel, under the action of the freewheeling diode in the power driving module, the reverse electromotive force enables the MOS transistor Q7 to be reversely conducted, the reverse electromotive force generated by the three-phase winding effectively forms a passage by the corresponding freewheeling diode in the power driving module, the freewheeling of the conducted MOS transistor Q7 eliminates the residual magnetic capacitor C2 to store energy,

the singlechip outputs an opening control signal to control the monitoring module to monitor the opening voltage;

Thirdly, recognizing that demagnetization is finished according to the sampling voltage change trend:

the singlechip outputs a turn-off control signal to the grid electrode of the MOS tube Q7, the MOS tube Q7 is turned off,

the singlechip outputs a closing control signal to control the monitoring module to close voltage monitoring, so that the electric quantity on the capacitor C2 is effectively prevented from losing and energy is saved;

when the demagnetization is considered to be finished in advance, the parasitic diode in the MOS transistor Q7 is used for switching on the MOS transistor Q7 to participate in the follow current elimination of the residual magnetic capacitor C2 for storing energy until the follow current is finished completely;

when the demagnetization is determined to be finished after the hysteresis, the MOS tube Q7 becomes forward conduction in the hysteresis time, but the follow current diode is used for follow current in the power driving module, so that the situation that the electric quantity stored in the capacitor C2 flows into the motor winding wrongly is effectively avoided;

when the method is used for starting, the singlechip controls the MOS tube Q7 to be conducted and turned off in a time-limited manner, so that the motor is started in a time-limited manner by high-voltage excitation.

The beneficial effects are that:

the invention discloses a follow current energy storage demagnetizing device of a permanent magnet synchronous motor and an implementation method thereof, which not only keep a power driving module of the permanent magnet synchronous motor with a three-phase stator winding star connection method in the prior art unchanged and a control method for the power driving module of the permanent magnet synchronous motor, thereby effectively keeping the motor in effective work, but also realize:

(1) The voltage change of the capacitor C2 is sampled directly from two ends of the capacitor C2, or the voltage is indirectly obtained from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, so that the voltage of the voltage stabilizing tube is stabilized, the influence of the voltage of the power supply VDC on sampling precision is reduced, and then the voltage change of the capacitor C2 is sampled; the defect that the voltage change precision of the capacitor of the single chip microcomputer sampling energy storage is affected when the power supply voltage is stopped and the follow current energy storage is demagnetized in the prior art is effectively overcome, so that the sampling methods under different power supply voltages are unified into an effective voltage sampling method, the demagnetization is recognized to be finished under the same judgment precision, and corresponding control and prompt are carried out to a user;

(2) the monitoring module is in a closed state and is not electrified during the change of the capacitor voltage of the non-monitoring energy storage, so that the electric quantity on the capacitor C2 is effectively prevented from losing and energy is saved;

(3) the reverse electromotive force produced during shutdown is freewheeled in the power driving module by the freewheeling diode, so that the reverse electromotive force produced in the three-phase winding of the motor during shutdown in any running state can be freewheeled to store energy and eliminate remanence, and if demagnetization is confirmed to be finished with errors: when the hysteresis is caused, the MOS tube Q7 is completely cut off after demagnetization is judged, and the phenomenon of backflow current to a motor winding is avoided; when the demagnetization is considered to be finished in advance, the MOS transistor Q7 is turned off, and the parasitic diode is arranged in the MOS transistor Q7, so that the parasitic diode in the MOS transistor Q7 takes over the conduction of the parasitic diode to participate in the capacitor energy storage of the residual magnetic energy storage of the flywheel elimination until the flywheel is finished completely;

(4) The reverse electromotive force produced during shutdown is in freewheeling in the power driving module, and the parasitic diode is arranged in the MOS tube Q7, so that once the singlechip is in shutdown when power is lost, the reverse electromotive force in three phases still charges and eliminates residual magnetism to the capacitor C2 through the freewheeling diode in the power driving module and the parasitic diode freewheeling in the MOS tube Q7 until the freewheeling is finished;

(5) during shutdown, the MOS transistor Q7 is controlled to be conducted for follow current, and the main purpose of the control method is to relieve the load of parasitic diodes in the MOS transistor Q7 when the parasitic diodes are used for follow current, and certainly, the voltage on a capacitor can be effectively improved by conducting the follow current of the MOS transistor Q7.

Drawings

Fig. 1 is a schematic diagram of a power driving module of a permanent magnet synchronous motor with a star connection of three-phase stator windings in the prior art;

fig. 2 is a schematic diagram of a flywheel energy storage degaussing device of a permanent magnet synchronous motor according to the present invention based on monitoring the voltage change of an energy storage capacitor;

FIG. 3 is a schematic circuit diagram of a first embodiment of the monitoring module of FIG. 2;

FIG. 4 is a schematic diagram of a second embodiment of the monitoring module of FIG. 2;

FIG. 5 is a schematic circuit diagram of a third embodiment of the monitoring module of FIG. 2;

FIG. 6 is a schematic diagram of a flywheel energy storage degaussing device of a permanent magnet synchronous motor according to the present invention based on monitoring the change of the current in the charging loop of the energy storage capacitor;

In the figure: q1, Q2, Q3, Q4, Q5, Q6. Power driving tube, VDC. Power supply, C1, C2, C3. capacitor, VCC+. Positive pole of DC power supply, VCC_. Negative pole of DC power supply, Q7.MOS tube, DZ1, DZ2. Voltage stabilizing tube, T1, T2, T3, T4, T8. switch tube, U1, U2, U3, U4. photocoupler, R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, R18, R19. Resistor, VD1, VD2, VD3.

Detailed Description

As shown in fig. 1, power driving tubes Q1, Q2, Q3, Q4, Q5 and Q6 are six power driving tubes with freewheel diodes on bridge arms in a power driving module of a permanent magnet synchronous motor adopting a three-phase stator winding star connection method in the prior art, and are NMOS tubes or N-type IGBT modules; the power supply VDC is a direct current power supply for normally supplying power to a power driving module of the permanent magnet synchronous motor with a three-phase stator winding star connection method in the prior art; the capacitor C1 is used for filtering the power supply VDC in the prior art; the output ends of the singlechips D1, D2, D3, D4, D5 and D6 are respectively connected with the grid electrodes (control ends) of the corresponding power driving tubes Q1, Q2, Q3, Q4, Q5 and Q6, and the negative electrode of the singlechip working power supply is considered to be connected with the negative electrode of the power supply VDC; the power driving module is used for driving the permanent magnet synchronous motor to operate.

As shown in fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, the flywheel energy storage degaussing device of the permanent magnet synchronous motor based on the monitoring of the voltage change of the energy storage capacitor is additionally provided with a flywheel energy storage module and a monitoring module which is unified as a monitoring module for monitoring the degaussing completion condition of the voltage change of the energy storage capacitor on the basis of a power driving module of the permanent magnet synchronous motor based on a three-phase stator winding star connection method; the follow current energy storage module comprises a MOS tube Q7, a diode VD and an energy storage capacitor C2; disconnecting the positive electrode of the power supply VDC from a bus for supplying power to the power driving module, connecting the positive electrode of the power supply VDC in series with the diode VD, and then connecting the positive electrode of the power supply VDC to the bus for supplying power to the power driving module; the cathode of the capacitor C2 is connected with the anode of the power supply VDC, the anode of the capacitor C2 is connected with the drain electrode of the MOS tube Q7, the source electrode of the MOS tube Q7 is connected with the cathode of the diode VD, and the grid electrode of the MOS tube Q7 is connected with the output of the singlechip; the A/D input of the singlechip is connected with the output of the monitoring module, and the voltage change of the capacitor C2 is directly sampled from the two ends of the capacitor C2 through the monitoring module, or the voltage is indirectly obtained from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, so that the voltage of the voltage stabilizing tube is stabilized, the influence of the voltage of the power supply VDC on the sampling precision is reduced, and then the voltage change of the capacitor C2 is sampled.

The singlechip is additionally provided with a program module for controlling the on/off of the MOS tube Q7 and the on/off of the monitoring module, calculating the change rate and judging the corresponding voltage sampling, and an adaptive output end connected with the MOS tube Q7, a control output end connected with the monitoring module and an A/D input end.

The MOS transistor Q7 is an NMOS transistor and has a parasitic diode (the existence of the parasitic diode is not described in order to explain the present application, but the MOS transistor is not described in detail in order to show the difference since it is assumed that the parasitic diode is not included in the 3 applications filed on the same day in the background art).

The capacitor C2 is a capacitor for energy storage, and is used for charging and storing energy when the motor is stopped and freewheels to eliminate residual magnetism, and is overlapped with the voltage of the power supply VDC when the motor is started, and high voltage is applied to a bus for supplying power to a power driving module of the permanent magnet synchronous motor with the star connection of the three-phase stator winding, so that the motor is started under high voltage, the starting process is shortened, and the starting efficiency is improved.

The diode VD is used for supplying power to a bus for supplying power to the power driving module by the power source VDC via the diode VD during normal operation of the motor, and preventing freewheeling from directly forming a loop from the power source VDC during shutdown.

After the machine is stopped, the generated electromotive force in the three-phase winding is led to the bus through the corresponding freewheeling diode in the power driving module, the singlechip controls the MOS tube Q7 to be conducted, the conduction is reverse conduction, the generated electromotive force in the three-phase winding is freewheeled to the bus through the corresponding freewheeling diode in the power driving module, and the capacitor C2 is charged and demagnetized from the conduction MOS tube Q7 freewheeled.

After the machine is stopped, if the single chip microcomputer keeps controlling the MOS tube Q7 to be turned off, the generated forward electromotive force in the three-phase winding flows to the bus through the corresponding freewheeling diode in the power driving module, and the parasitic diode freewheels in the MOS tube Q7 to charge and demagnetize the capacitor C2.

After stopping, the singlechip controls the MOS tube Q7 to be conducted, in the process of charging and demagnetizing the capacitor C2 from the conducted MOS tube Q7, the singlechip judges whether the demagnetization is finished by sampling the voltage on the capacitor C2 through the monitoring module and calculating the change rate, and when the change rate is smaller than a set value, the singlechip determines that the demagnetization is finished, controls the MOS tube Q7 to be turned off, and the parasitic diode in the MOS tube Q7 continuously participates in charging the capacitor C2 from the follow current until the follow current is finished, and completely demagnetizes.

When the three-phase excitation starting motor is started, the MOS tube Q7 is controlled by the singlechip to be conducted and set to be turned off in a time limit mode, so that the capacitor C2 is overlapped with the voltage of the power supply VDC in the time limit mode, high voltage is applied to a bus for supplying power to a power driving module of the three-phase stator winding star connection permanent magnet synchronous motor through the conducted MOS tube Q7, and the three-phase excitation starting motor is excited by the high voltage; after the MOS tube Q7 is closed, a power supply VDC supplies power to the power driving module through a diode VD, and the motor runs normally. The MOS transistor Q7 is controlled to be turned on and turned off at the later time limit, just like the turn-off after 0.5S-1S described in the prior art.

The reverse electromotive force produced during shutdown still uses the freewheeling diode in the power driving module in the prior art to freewheel, so that the freewheeling energy storage and demagnetization can be effectively realized no matter the power driving module is electrified and shutdown in any state, and even if the monitored residual magnetism elimination completion condition has errors, the freewheeling demagnetization is actually finished, the MOS tube Q7 is still in a conducting state, and the phenomenon of backflow current to the phase does not occur; because parasitic diodes exist in the MOS tube Q7, even if the monitored situation of eliminating residual magnetism has errors, the actual follow current degaussing is not complete yet, the MOS tube Q7 is controlled to be turned off, and at the moment, although the MOS tube Q7 is turned off, the parasitic diodes in the MOS tube Q7 continue to participate in follow current energy storage degaussing until the follow current is finished, and the follow current is completely degaussed; when the motor is stopped, residual magnetism can be effectively eliminated through high-voltage energy storage, high-voltage excitation is started during starting, and normal operation of the motor is not influenced; and stopping the motor once the singlechip is powered off, and charging and eliminating residual magnetism to the energy storage capacitor still through the freewheeling diode in the power driving module and the parasitic diode in the MOS tube Q7 by the reverse electromotive force in the three phases until the freewheeling is finished and completely demagnetizing.

As shown in fig. 3, in the circuit of the first embodiment of the monitoring module, a voltage is obtained from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, and the voltage is indirectly obtained after the voltage disturbance of the power supply VDC is filtered by the voltage stabilizing tube DZ 1; the monitoring module comprises a voltage stabilizing tube DZ1, a switching tube T2, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5; the cathode of the voltage stabilizing tube DZ1 is connected with the positive electrode of the capacitor C2, the anode of the voltage stabilizing tube DZ1 is connected with the high potential end of the switch tube T1, the low potential end of the switch tube T1 is connected with the negative electrode of the power supply VDC after being connected with the resistor R1 and the resistor R2 in series, the connection position of the resistor R1 and the resistor R2 is connected with the A/D input of the singlechip through a lead wire, the control end of the switch tube T1 is connected with the high potential end of the switch tube T2 after being connected with the high potential end of the switch tube T2 in series, the low potential end of the switch tube T2 is connected with the negative electrode of the power supply VDC, the control end of the switch tube T2 is respectively connected with one end of the resistor R4 and one end of the resistor R5, the other end of the resistor R4 is connected with the negative electrode of the power supply VDC, and the other end of the resistor R5 is connected with the output of the singlechip I/O.

The switch tube T1 is a PNP switch triode or a PMOS tube or a P-type IGBT tube; when the switching tube T1 is a PNP type switching triode, the high potential end is the emitter of the PNP type switching triode, the low potential end is the collector of the PNP type switching triode, and the control end is the base of the PNP type switching triode; when the switch tube T1 is a PMOS tube, the high potential end is the source electrode of the PMOS tube, the low potential end is the drain electrode of the PMOS tube, and the control end is the grid electrode of the PMOS tube; when the switching tube T1 is a P-type IGBT tube, the high potential end is the emitter of the P-type IGBT tube, the low potential end is the collector of the P-type IGBT tube, and the control end is the grid of the P-type IGBT tube. The switching transistor T1 is preferably a PNP switching transistor.

The switch tube T2 is an NPN switch triode or an NMOS tube or an N IGBT tube; when the switching tube T2 is an NPN type switching triode, the high potential end is the collector electrode of the NPN type switching triode, the low potential end is the emitter electrode of the NPN type switching triode, and the control end is the base electrode of the NPN type switching triode; when the switching tube T2 is an NMOS tube, the high potential end is the drain electrode of the NMOS tube, the low potential end is the source electrode of the NMOS tube, and the control end is the grid electrode of the NMOS tube; when the switching tube T2 is an N-type IGBT tube, the high potential end is the collector of the N-type IGBT tube, the low potential end is the emitter of the N-type IGBT tube, and the control end is the grid of the N-type IGBT tube. The switching transistor T2 is preferably an NPN-type switching transistor.

The above-mentioned voltage stabilizing value selection of the voltage stabilizing tube DZ1 should satisfy: the voltage of the power supply VDC minus the voltage stabilizing value of the voltage stabilizing tube DZ1 is larger than zero and smaller than or equal to 48V; considering that when no voltage is stopped at two ends of the capacitor C2 for energy storage, the saturated conduction operation of the switching tube T1 in the monitoring module can be timely and effectively controlled, so that the voltage stabilizing value of the voltage stabilizing tube DZ1 is not equal to the voltage of the power supply VDC, but the voltage stabilizing value of the voltage stabilizing tube DZ1 is closer to the voltage of the power supply VDC, and the voltage of the power supply VDC has smaller influence on the monitoring effect; in order to effectively control the saturated conduction operation of the switching tube T1 in the monitoring circuit in time when no voltage is stopped at the two ends of the capacitor C2, the voltage stabilizing value of the voltage stabilizing tube DZ1 is preferably a voltage stabilizing value plus the voltage required by effectively controlling the saturated conduction operation of the switching tube T1 in the monitoring circuit to be equal to the voltage of the power supply VDC, namely, the voltage stabilizing value of the voltage stabilizing tube DZ1 is preferably selected plus the voltage of 10V which is equal to the voltage of the power supply VDC, and if the voltage of the working power supply VDC of the permanent magnet synchronous motor is less than or equal to 10V, the voltage stabilizing tube DZ1 is removed.

The resistor R1 and the resistor R2 are connected in series to form a sampling circuit, so that voltage variation on the capacitor C2 is obtained through voltage division and is output to the singlechip, namely the singlechip samples voltage from the resistor R2 of which the resistor R1 and the resistor R2 are connected in series.

The resistor 4 and the resistor R5 are limiting/current limiting resistors at the control end of the switching tube T2.

The resistor 3 is a limiting/current-limiting resistor at the control end of the switching tube T1.

The working procedure of the circuit of the first embodiment of the above monitoring module is:

when the power supply is stopped, the singlechip controls the MOS tube Q7 to be conducted, the singlechip outputs high level to the control end of the switch tube T2, the switch tube T2 is saturated and conducted, 10V is added between the high potential end of the switch tube T1 and the negative electrode of the power supply VDC because the voltage stabilizing value of the voltage stabilizing tube DZ1 is set to be smaller than the voltage of the power supply VDC by 10V, thereby a control signal is sent to the control end of the switch tube T1 through the resistor R3 to enable the switch tube T1 to be saturated and conducted, after the switch tube T1 is conducted, the voltage of the capacitor C2 is charged to the capacitor C2, the voltage of the capacitor C2 is indirectly reflected at the two ends of the resistor R1 and the resistor R2 which are connected in series, the influence of the voltage of the power supply VDC on the two ends of the resistor R1 and the resistor R2 which are connected in series is only 10V, therefore, the defect that the voltage variation of the power supply VDC voltage on the sampling capacitor C2 of the single chip microcomputer is not obvious is effectively filtered through the voltage stabilization of the voltage stabilizing tube DZ1, the measuring range of the voltage variation on the capacitor C2 in the process of sampling, stopping and freewheeling of the single chip microcomputer through the resistor R2 is effectively enlarged, the single chip microcomputer can effectively calculate the change rate through the voltage variation on the capacitor C2 in the process of sampling, stopping and freewheeling of the resistor R2 no matter whether the power supply VDC is less than or equal to 48V or greater than 48V, when the change rate is detected to be close to zero or less than a set value, the demagnetization is considered to be finished, the MOS tube Q7 which is controlled to be conducted is turned off, and the parasitic diode in the MOS tube Q7 continues freewheeling to store energy to the capacitor C2 and eliminate residual magnetism until the freewheeling is ended, and the demagnetization is completely demagnetized.

When the degaussing is determined to be completed and the MOS transistor Q7 which is controlled to be conducted is turned off, a low level is output to the control end of the switching tube T2, the switching tube T2 is turned off, the switching tube T1 is turned off, and the monitoring module of the circuit in the first embodiment is not electrified and saves energy.

As shown in fig. 4, in the circuit of the second embodiment of the monitoring module, a voltage is obtained from the positive electrode of the capacitor C2 to the negative electrode of the power supply VDC, and the voltage is indirectly obtained after the voltage disturbance of the power supply VDC is filtered by the voltage stabilizing tube DZ 2; the monitoring module comprises a voltage stabilizing tube DZ2, a switch tube T3, a photoelectric coupler U1, a resistor R6, a resistor R7, a resistor R8, a resistor R9 and a resistor R10, wherein the cathode of the voltage stabilizing tube DZ2 is connected with the positive electrode of a capacitor C2, the anode of the voltage stabilizing tube DZ2 is connected with the collector of a phototriode in the photoelectric coupler U1, the emitter of the phototriode in the photoelectric coupler U1 is connected with the resistor R6 and the negative electrode of a power supply VDC in series in sequence, the junction of the resistor R6 and the resistor R7 is connected with the A/D input of a singlechip through leads, the anode of a light emitting diode in the photoelectric coupler U1 is connected with the power supply of the singlechip after being connected with the resistor R8 in series, the cathode of the light emitting diode in the photoelectric coupler U1 is connected with the high potential end of the switch tube T3, the low potential end of the switch tube T3 is connected with the negative electrode of the power supply VDC, the control end of the switch tube T3 is respectively connected with one end of the resistor R9 and one end of the resistor R10, the other end of the resistor R9 is connected with the negative electrode of the power supply VDC, and the other end of the resistor R10 is connected with the output of the singlechip.

The switch tube T3 is an NPN switch triode or an NMOS tube or an N IGBT tube; when the switching tube T3 is an NPN type switching triode, the high potential end is the collector electrode of the NPN type switching triode, the low potential end is the emitter electrode of the NPN type switching triode, and the control end is the base electrode of the NPN type switching triode; when the switching tube T3 is an NMOS tube, the high potential end is the drain electrode of the NMOS tube, the low potential end is the source electrode of the NMOS tube, and the control end is the grid electrode of the NMOS tube; when the switching tube T3 is an N-type IGBT tube, the high potential end is the collector of the N-type IGBT tube, the low potential end is the emitter of the N-type IGBT tube, and the control end is the grid of the N-type IGBT tube. The switching transistor T3 is preferably an NPN-type switching transistor.

Resistor R8 is the current limiting resistor of the light emitting diode in optocoupler U1.

The resistor R9 and the resistor R10 are limiting/current limiting resistors at the control end of the switching tube T3.

The above-mentioned voltage stabilizing value selection of the voltage stabilizing tube DZ2 should satisfy: the voltage of the power supply VDC minus the voltage stabilizing value of the voltage stabilizing tube DZ2 is larger than zero and smaller than or equal to 48V; considering that when no voltage is stopped at two ends of the capacitor C2 for energy storage, the phototriode in the photoelectric coupler U1 can be timely and effectively conducted to work, so that the voltage stabilizing value of the voltage stabilizing tube DZ2 is not equal to the voltage of the power supply VDC, but the voltage stabilizing value of the voltage stabilizing tube DZ2 is closer to the voltage of the power supply VDC, and the voltage of the power supply VDC has smaller influence on the monitoring effect. The regulated value of the regulator tube DZ2 in this embodiment is preferably less than 2V, which is the voltage of the power source VDC.

The resistor R6 and the resistor R7 are connected in series to form a sampling circuit so as to obtain voltage variation on the capacitor C2 through voltage division and output the voltage variation to the singlechip, namely the singlechip samples voltage from the resistor R7 of which the resistor R6 and the resistor R7 are connected in series.

The working procedure of the circuit of the second embodiment of the above monitoring module is:

when the power supply is stopped, the singlechip controls the MOS tube Q7 to be conducted, the singlechip outputs high level to the control end of the switching tube T3, the switching tube T3 is saturated and conducted, the light-emitting diode in the photoelectric coupler U1 is electrified and emits light, the phototriode in the photoelectric coupler U1 is saturated and conducted, after the conduction, the voltage of the capacitor C2 is charged into the capacitor C2 and indirectly reflected at two ends of the series connection of the resistor R6 and the resistor R7, the voltage of the power supply VDC is filtered out by the voltage stabilizing tube DZ2, the rest part is added at two ends of the series connection of the resistor R6 and the resistor R7, thereby effectively stabilizing the voltage by the voltage stabilizing tube DZ2 and filtering the defect that the voltage of the power supply VDC is not obvious to the voltage change of the singlechip sampling capacitor C2, the measuring range of voltage change on the capacitor C2 in the shutdown freewheel process of the singlechip through the resistor R7 is effectively enlarged, so that the singlechip can effectively calculate the change rate through the voltage change on the capacitor C2 in the shutdown freewheel process of the resistor R7 no matter whether the power supply VDC is less than or equal to 48V or more than 48V, when the change rate is detected to be close to zero or less than a set value, demagnetization is considered to be completed, the conducted MOS tube Q7 is controlled to be turned off, and the parasitic diode in the MOS tube Q7 continuously freewheel stores energy to the capacitor C2 and eliminates residual magnetism until the freewheel is finished, and the demagnetization is completed.

When the demagnetization is judged to be finished and the MOS transistor Q7 which is controlled to be conducted is turned off, a low level is output to the control end of the switching tube T3, the switching tube T3 is turned off, when the light emitting diode in the photoelectric coupler U1 is not electrified, the phototriode in the photoelectric coupler U1 is turned off, and the monitoring module of the circuit in the second embodiment is not electrified and saves energy.

As shown in FIG. 5, the third embodiment of the monitoring module is implemented by directly obtaining voltages from two ends of a capacitor C2 to take samples, so as to eliminate the influence of the voltage of a power supply VDC on the voltage variation of a single chip microcomputer sampling capacitor C2, wherein the monitoring module comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a photoelectric coupler U2, a photoelectric coupler U3 and a switch T4, the anode of a light emitting diode in the photoelectric coupler U2 is connected with the positive electrode of the capacitor C2 after being connected with the resistor R11 in series, the cathode of the light emitting diode in the photoelectric coupler U2 is connected with the collector of a phototriode in the photoelectric coupler U3, the emitter of the phototriode in the phototriode U3 is connected with the negative electrode of the capacitor C2, the anode of the light emitting diode in series with the resistor R13 in the photoelectric coupler U3 is connected with the power supply of the single chip microcomputer, the cathode of the light emitting diode in the photoelectric coupler U3 is connected with the high potential end of the switch T4, the low potential end of the switch T4 is connected with the negative electrode of the power supply, the control end of the light emitting diode is connected with the control end of the LED in the triode T4 and the negative electrode of the resistor R16 in series with the phototriode R14, the phototriode is connected with the negative electrode of the phototriode I2, and the phototriode I is connected with the phototriode I2 in series after being connected with the cathode of the phototriode I2.

The switch tube T4 is an NPN switch triode or an NMOS tube or an N IGBT tube; when the switching tube T4 is an NPN type switching triode, the high potential end is the collector electrode of the NPN type switching triode, the low potential end is the emitter electrode of the NPN type switching triode, and the control end is the base electrode of the NPN type switching triode; when the switching tube T4 is an NMOS tube, the high potential end is the drain electrode of the NMOS tube, the low potential end is the source electrode of the NMOS tube, and the control end is the grid electrode of the NMOS tube; when the switching tube T4 is an N-type IGBT tube, the high potential end is the collector of the N-type IGBT tube, the low potential end is the emitter of the N-type IGBT tube, and the control end is the grid of the N-type IGBT tube. The switching transistor T4 is preferably an NPN-type switching transistor.

The photoelectric coupler U3 is a digital photoelectric coupler, when the light emitting diode in the photoelectric coupler U3 is electrified, the phototriode in the photoelectric coupler U3 is saturated and conducted, and when the light emitting diode in the photoelectric coupler U3 is not electrified, the phototriode in the photoelectric coupler U3 is cut off.

Resistor R13 is the current limiting resistor of the light emitting diode in optocoupler U3.

The resistor R14 and the resistor R15 are limiting/current limiting resistors at the control end of the switching tube T4.

The photo coupler U2 is a linear photo coupler, the light emitting diode indirectly obtains the voltage change on the capacitor C2 through current response, and is coupled with the corresponding phototransistor in a linear relationship, the current in the phototransistor changes in a linear corresponding relationship with the current change in the light emitting diode, and thus the singlechip indirectly samples the voltage change on the capacitor C2 on the resistor R16 to calculate the change rate.

The resistor R11 and the light emitting diode in the photoelectric coupler U2 are connected in series to form a sampling circuit so as to obtain the voltage change on the capacitor C2 and convert the voltage change into corresponding current, namely the light emitting diode in the photoelectric coupler U2 indirectly obtains the voltage change on the capacitor C2 through current response and is coupled with the corresponding phototriode in a linear relationship, the current in the phototriode changes along with the current in the light emitting diode in a linear corresponding relationship, and the current in the phototriode then changes along with the corresponding voltage change on the resistor R16. Namely: at this time, the monitoring module is equivalent to directly obtaining the voltage change on the capacitor C2 and outputting the voltage change to the singlechip.

The resistor R11 is a current limiting resistor for the light emitting diode in the photo coupler U2 and the light emitting diode in the photo coupler U3.

Resistor R12 is a phototransistor current limiting resistor in optocoupler U2.

The working procedure of the circuit of the third embodiment of the above monitoring module is as follows:

when the device is stopped, the singlechip controls the MOS tube Q7 to be conducted, the singlechip outputs a high level to the control end of the switching tube T4, the switching tube T4 is saturated and conducted, thereby the light emitting diode in the photoelectric coupler U3 is electrified and emits light, the phototriode in the photoelectric coupler U3 is saturated and conducted, after the conduction, the capacitor C2 is charged, the voltage of the capacitor C2 is reflected at two ends of the series connection of the resistor R11 and the light emitting diode in the photoelectric coupler U2, the through-flow of the light emitting diode in the photoelectric coupler U2 is linearly changed along with the voltage of the two ends of the capacitor C2, the phototriode in the photoelectric coupler U2 forms a corresponding linear change current, the sampled voltage is indirectly reflected on the resistor R16, the defect that the voltage of the power VDC voltage of the singlechip is not obvious to the sampled capacitor C2 is overcome, the measuring range of the voltage change of the capacitor C2 in the sampling stopping and freewheeling process is effectively enlarged, no matter whether the power source VDC is less than 48V or not more than 48V, the singlechip can indirectly stop the voltage change of the capacitor C2 in the process through the resistor R16 is stopped indirectly, the voltage change of the capacitor C2 is close to the zero or the zero when the voltage change is detected to be completely stopped, the parasitic factor is completely, and the parasitic factor is completely stopped, and the value is completely controlled by the Q7 is stopped, and the parasitic factor is completely stopped, and the value is completely stopped when the parasitic factor is controlled.

When the demagnetization is determined to be finished and the MOS transistor Q7 which is controlled to be conducted is turned off, a low level is output to the control end of the switching tube T4, the switching tube T4 is turned off, when the light emitting diode in the photoelectric coupler U3 is not electrified, the phototriode in the photoelectric coupler U3 is turned off, and the monitoring module of the circuit in the third embodiment is not electrified and saves energy.

The invention discloses an implementation method of a follow current energy storage demagnetizing device of a permanent magnet synchronous motor based on monitoring of voltage change of an energy storage capacitor, which comprises the following steps:

and (3) when the machine is stopped:

As shown in fig. 6, the flywheel energy storage and degaussing device of the permanent magnet synchronous motor based on the monitoring of the change of the current of the energy storage capacitor charging loop is additionally provided with a flywheel energy storage module and a monitoring module which is unified as a monitoring module for monitoring the completion condition of degaussing of the change of the current of the energy storage capacitor charging loop on the basis of a power driving module of the permanent magnet synchronous motor based on a three-phase stator winding star connection method; the follow current energy storage module comprises a switching tube T8, a diode VD1, a diode VD2, a diode VD3 and an energy storage capacitor C3; disconnecting the positive electrode of the power supply VDC from a bus for supplying power to the power driving module, and connecting the positive electrode of the power supply VDC to the bus for supplying power to the power driving module after connecting the diode VD1 in series; the cathode of the capacitor C3 is connected with the anode of the power supply VDC, the anode of the capacitor C3 is connected with the high potential end of the switching tube T8, the low potential end of the switching tube T8 is connected with the cathode of the diode VD1, and the control end of the switching tube T8 is connected with the output of the singlechip; the diode VD3 and the diode VD2 are connected in series in the forward direction to form a freewheeling diode in the freewheeling energy storage module, and the sampling circuit in the monitoring module is used for acquiring sampling voltages from two ends of the diode VD3 and the diode VD2 which are connected in series in the forward direction, so that the singlechip effectively samples small current in the capacitor charging loop through the monitoring module; the cathode of the diode VD2 is connected to the high potential end of the switching tube T8, the anode of the diode VD2 is connected with the cathode of the diode VD3, and the anode of the diode VD3 is connected to a bus of the power supply of the power driving module; the monitoring module comprises a photoelectric coupler U4, a resistor R17, a resistor R18 and a resistor R19; the resistor 19 and the light emitting diode in the photoelectric coupler U4 are connected in series to form a sampling circuit, the anode of the light emitting diode in the photoelectric coupler U4 is connected with the anode of the diode VD3, and the cathode of the light emitting diode in the photoelectric coupler U4 is connected in series with the resistor R19 and then connected with the cathode of the diode VD 2; the emitter of the phototriode in the photoelectric coupler U4 is connected with the negative electrode of the power supply VDC after being connected with the resistor R18 in series, and the emitter lead of the phototriode in the photoelectric coupler U4 is connected with the A/D input of the singlechip, and the collector of the phototriode in the photoelectric coupler U4 is connected with the power supply of the singlechip after being connected with the resistor R17 in series.

The singlechip is additionally provided with a program module for controlling the on/off of the switching tube T8 and judging the sampling and the change of the current, an adaptive output end connected with the switching tube T8 and an A/D input end connected with the output of the monitoring module.

The switch tube T8 is an NPN switch triode or an N IGBT tube; when the switching tube T8 is an NPN type switching triode, the high potential end is the collector electrode of the NPN type switching triode, the low potential end is the emitter electrode of the NPN type switching triode, and the control end is the base electrode of the NPN type switching triode; when the switching tube T8 is an N-type IGBT tube, the high potential end is the collector of the N-type IGBT tube, the low potential end is the emitter of the N-type IGBT tube, and the control end is the grid of the N-type IGBT tube. The switching tube T8 is preferably an N-type IGBT tube. The switching tube T8 is turned on only when the motor is started.

The capacitor C3 is a capacitor for energy storage, and is used for charging and storing energy when the motor is stopped and freewheels to eliminate residual magnetism, and is overlapped with the voltage of the power supply VDC when the motor is started, and high voltage is applied to a bus for supplying power to a power driving module of the permanent magnet synchronous motor with the star connection of the three-phase stator winding, so that the motor is started under high voltage, the starting process is shortened, and the starting efficiency is improved.

The diode VD1 is used for supplying power to a bus for supplying power to the power driving module by the power source VDC through the diode VD1 when the motor is in normal operation, and preventing the freewheeling from directly forming a loop from the power source VDC when the motor is stopped.

When starting, the singlechip controls the switching tube T8 to be conducted and sets time limit to be turned off, so that the capacitor C3 is overlapped with the voltage of the power supply VDC in time limit, and high voltage is applied to a bus for supplying power to a power driving module of the permanent magnet synchronous motor of the three-phase stator winding star connection method through the conducted switching tube T8, and the three-phase excitation starting motor is excited by the high voltage; after the switching tube T8 is closed, the power source VDC supplies power to the power driving module through the diode VD1, and the motor runs normally. The switching tube T8 is controlled to be turned on and turned off at the rear limit, just like the switching tube T is turned off after 0.5S-1S recorded in the prior art.

The photoelectric coupler U4 is a linear optocoupler and is used for sampling current in a shutdown follow current energy storage degaussing process, the light emitting diode in the photoelectric coupler U4 is used for specifically sampling the current of the capacitor charging loop for the acquisition circuit, the current change of the phototriode in the photoelectric coupler U4 is controlled by the linear coupling, the current change of the phototriode forms corresponding voltage change on the resistor R18, and the singlechip calculates the current passing through the light emitting diode of the photoelectric coupler U4 through the voltage on the sampling resistor R18. The resistor R19 is used for current limiting protection and current adjustment of the light emitting diode in the photocoupler U4.

Resistor R17 is the current limiting resistor of the phototransistor in the optocoupler U4.

The diode VD3 and the diode VD2 are connected in series in the forward direction and then used for stopping the continuous current during continuous current energy storage and demagnetization, and the purpose of adopting the two diodes connected in series as the continuous current diode is as follows: the light emitting diode in the photoelectric coupler U4 of the monitoring module obtains sampling voltage from two ends of the freewheeling diode, so that the freewheeling diode in the capacitor charging loop is connected in series forward by adopting two diodes in order to ensure that the light emitting diode in the photoelectric coupler U4 works effectively. Diodes VD3 and VD2 in this embodiment are each selected to be silicon diodes, or one is a silicon diode and the other is a germanium diode.

In the shutdown follow current energy storage degaussing process, when the voltage generated at two ends of the diode VD3 and the diode VD2 after being connected in series in the forward direction is equal to the sum of the conducting voltages of the diode VD3 and the diode VD2, the follow current energy storage degaussing is indicated to be in normal operation, that is, degaussing is not effectively finished yet, and when the diode VD3 and the diode VD2 are in conduction, the voltage at two ends of the diode serial resistor R19 added in the photoelectric coupler U4 is constant, that is, the voltage is equal to the sum of the conducting voltages of the diode VD3 and the diode VD2, so that when the diode VD3 and the diode VD2 are in conduction, the current flowing through the diode in the photoelectric coupler U4 is constant, and the constant current depends on the resistance value of the resistor R19.

In the shutdown follow current energy storage degaussing process, the current in the capacitor charging loop is equal to the sum of the current flowing through the light emitting diode in the photoelectric coupler U4 and the current flowing through the series diode VD3 and the diode VD 2; when the diode VD3 and the diode VD2 are in conduction, the current in the capacitor charging loop almost flows from the conducted diode VD3 and the diode VD2, namely, the sum of the conducted diode VD3 and the diode VD current and the constant current flowing through the light emitting diode in the photoelectric coupler U4; when the follow current energy storage demagnetizing process advances, the follow current energy is weakened gradually, the diode VD3 and the diode VD2 are turned from conduction to non-effective conduction and non-conduction gradually, and the follow current energy storage demagnetizing is finished.

When the diode VD3 and the diode VD2 become not effectively conductive and non-conductive, the voltages at the two ends of the diode VD3 and the diode VD2 connected in series in the forward direction are smaller than the sum of the conductive voltages of the diode VD3 and the diode VD2, so that the current flowing through the light emitting diode in the photo coupler U4 is smaller than the constant current flowing through the light emitting diode at the same time, and the current flowing through the light emitting diode in the photo coupler U4 is equal to the current of the capacitor charging loop at the moment.

And as is well known to those skilled in the art, when the flywheel is demagnetized during stopping, the flywheel diode is turned from conduction to non-effective conduction and non-conduction during the flywheel process, so that the end of demagnetization can be considered.

In this embodiment, the constant current flowing through the light emitting diode in the photo coupler U4 may be obtained by pre-measurement or calculation, or may be obtained by sampling in real time when the machine stops for freewheeling energy storage and demagnetization.

In this embodiment, when the diode VD3 and the diode VD2 are turned on, the resistance value of the resistor R19 is selected to make the constant current be less than 0.5% of the rated current of the motor in the prior art due to the physical characteristics of the optocoupler U4 in the effective working area of the light emitting diode in the optocoupler U4, and if the constant current is greater than 0.5% of the rated current of the motor in the prior art, the resistance value of the resistor R19 is increased to make the constant current be less than 0.5% of the rated current of the motor in the prior art.

Therefore, in the embodiment, during the shutdown flywheel energy storage degaussing process, the singlechip samples that the current flowing through the light emitting diode in the photoelectric coupler U4 is smaller than the constant current through the monitoring module, and the end of degaussing can be determined. In order to more effectively identify the end of demagnetization, it is preferable that: when the current change of the capacitor charging loop for energy storage is monitored to finish degaussing, the singlechip samples that the current flowing through the light-emitting diode in the photoelectric coupler U4 is less than 50% of constant current through the monitoring module, and the degaussing is judged to be finished.

The invention discloses an implementation method of a follow current energy storage demagnetizing device of a permanent magnet synchronous motor based on monitoring of the change of the current of an energy storage capacitor charging loop, which comprises the following steps:

the method comprises the steps that for different voltage of a power supply VDC (direct current) is unified as a change of a capacitor charging loop current for energy storage, as a condition for judging whether demagnetization is completed or not, a freewheeling diode in a freewheeling energy storage module is formed by connecting a diode VD3 and a diode VD2 in series in the forward direction, a resistor 19 in a monitoring module and a light-emitting diode in a photoelectric coupler U4 are connected in series to form a sampling circuit, the sampling circuit is connected at two ends of the diode VD3 and the diode VD2 which are connected in series in the forward direction in parallel, and the two ends of the diode VD3 and the diode VD2 which are connected in series in a sampling mode conduct voltage and small current in the capacitor charging loop current;

the method comprises the steps that (1) when a machine is stopped, reverse electromotive force generated by a three-phase winding is used for storing energy to a capacitor C3 to eliminate remanence through a freewheeling diode in a power driving module and a diode VD3 and a diode VD2 freewheeled in series in a freewheeling energy storage module, and meanwhile, a singlechip collects current flowing in an acquisition circuit under the condition that the diode VD3 and the diode VD2 are conducted through a monitoring module, and the current is set to be constant current and temporarily stored;

after temporary storage of constant current, the singlechip continuously monitors current in an acquisition circuit through the monitoring module, compares the current with the temporary storage of constant current, and determines that demagnetization is finished when the current in the acquisition circuit is monitored to be less than 50% of the constant current;

When the starter is started, the singlechip controls the switch tube T8 to be turned on and turned off in a time-limited manner, so that the starter motor is excited at high voltage in the time-limited period.

The follow current energy storage demagnetizing device of the permanent magnet synchronous motor based on the monitoring of the change of the current of the energy storage capacitor charging loop and the realization method thereof have the beneficial effects that:

the power driving module of the permanent magnet synchronous motor with the star connection method of the three-phase stator winding in the prior art and the control method of the power driving module are not changed, so that the motor can effectively work, and the method further realizes:

(1) the sampling circuit is connected with the flywheel diode in the flywheel energy storage module in parallel to effectively sample the small current in the capacitor charging loop current, so that the defect that the large and small loop current cannot be effectively considered in the prior art is overcome, the change of the capacitor charging loop current for energy storage is effectively monitored for different power supply VDC voltages uniformly, and the condition for judging whether demagnetization is finished or not is adopted, so that the demagnetization is judged to finish prompting a user, and the effective operation of the motor is not influenced;

(2) the reverse electromotive force generated by the three-phase winding is used for driving the freewheeling diode in the module and freewheeling the freewheeling diode in the freewheeling energy storage module, so that the machine is stopped once the singlechip is powered off, the reverse electromotive force freewheels in the three-phase winding are not influenced to charge the capacitor C3 and eliminate residual magnetism, and the freewheels are ended.

(3) Due to the reverse choke action of the light emitting diode of the photoelectric coupler U4 in the sampling circuit of the monitoring module, the electric quantity on the capacitor C3 can not be lost effectively in the non-stop follow current energy storage degaussing period.

Claims

1. The follow current energy storage demagnetizing device of the permanent magnet synchronous motor is characterized by comprising a power driving module of the permanent magnet synchronous motor with a three-phase stator winding star connection method, a follow current energy storage module and a monitoring module for monitoring the demagnetization completion condition by unifying sampling and energy storage capacitor voltage changes for different power supply VDC voltages; the follow current energy storage module comprises a MOS tube Q7, a diode VD and an energy storage capacitor C2; disconnecting the positive electrode of the power supply VDC from a bus for supplying power to the power driving module, connecting the positive electrode of the power supply VDC in series with the diode VD, and then connecting the positive electrode of the power supply VDC to the bus for supplying power to the power driving module; the cathode of the capacitor C2 is connected with the anode of the power supply VDC, the anode of the capacitor C2 is connected with the drain electrode of the MOS tube Q7, the source electrode of the MOS tube Q7 is connected with the cathode of the diode VD, the grid electrode of the MOS tube Q7 is connected with the output of the singlechip, and a parasitic diode is arranged in the MOS tube Q7; the A/D input of the singlechip is connected with the output of a monitoring module, the monitoring module directly adopts the voltage change of a capacitor C2 from two ends of the capacitor C2 to eliminate the influence of the voltage of a power supply VDC on sampling precision, and the monitoring module comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a photoelectric coupler U2, a photoelectric coupler U3 and a switching tube T4; the capacitor C2 is used for directly acquiring voltages from two ends of the capacitor C2 to carry out sampling; the anode of the light emitting diode in the photoelectric coupler U2 is connected with the positive electrode of the capacitor C2 after being connected with the resistor R11 in series, the cathode of the light emitting diode in the photoelectric coupler U2 is connected with the collector of the phototriode in the photoelectric coupler U3, the emitter of the phototriode in the photoelectric coupler U3 is connected with the negative electrode of the capacitor C2, the anode of the light emitting diode in the photoelectric coupler U3 is connected with the resistor R13 in series and then is connected with the power supply of the singlechip, the cathode of the light emitting diode in the photoelectric coupler U3 is connected with the high potential end of the switch tube T4, the low potential end of the switch tube T4 is connected with the negative electrode of the power supply VDC, the control end of the switch tube T4 is respectively connected with one end of the resistor R14 and one end of the resistor R15, the other end of the resistor R14 is connected with the negative electrode of the power supply VDC, the other end of the resistor R15 is connected with the output of the singlechip I/O, the collector of the phototriode in series with the phototriode in the photoelectric coupler U2 is connected with the singlechip after being connected with the resistor R12, the emitter of the phototriode in series with the singlechip is connected with the negative electrode of the power supply of the singlechip, the cathode of the phototriode in the photoelectric coupler U2 is connected with the phototriode in series with the cathode of the phototriode C2, the photocoupler A2 is connected with the phototriode in the photocoupler A11, the photocoupler is connected with the photocoupler U2 is connected with the photocoupler A, and the photocoupler is connected with the photocoupler A3, and the photocoupler is connected with the photocoupler is connected.

2. A method for implementing a flywheel energy storage degaussing device of a permanent magnet synchronous motor according to claim 1, comprising the steps of:

the method comprises the steps that voltage changes of a capacitor C2 are uniformly sampled and monitored for different power supply VDC voltages, and as a condition for judging whether demagnetization is completed or not, a singlechip directly samples the voltage changes of the capacitor C2 from two ends of the capacitor C2 through a monitoring module;

and (3) when the machine is stopped: