CN106341068B - Switching device for motor wide speed - Google Patents
Switching device for motor wide speed Download PDFInfo
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- CN106341068B CN106341068B CN201610899171.1A CN201610899171A CN106341068B CN 106341068 B CN106341068 B CN 106341068B CN 201610899171 A CN201610899171 A CN 201610899171A CN 106341068 B CN106341068 B CN 106341068B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
- H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
- H02P25/188—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays wherein the motor windings are switched from series to parallel or vice versa to control speed or torque
Abstract
The invention discloses a switching device for the wide speed of a motor, which comprises a power supply module, a series-parallel switching module and a PWM (pulse width modulation) and power driving module, wherein the series-parallel switching module comprises N switching units, each switching unit comprises a first switching switch, a second switching switch and a third switching switch, and the PWM and power driving module is respectively connected with the power supply module and the series-parallel switching module. The invention only needs to use an independent power supply, has simple structure and lower cost, and can not damage the change-over switch. And by controlling the on and off of the change-over switch in the series-parallel connection change-over module, various series-parallel connection states can be realized. Especially, under the condition of more windings of the motor, the high-efficiency rotating speed area of the motor can be multiplied, and the performance of the motor is greatly improved.
Description
Technical Field
The invention relates to the field of motors and control thereof, in particular to a switching device for the wide speed of a motor.
Background
As is known, the maximum efficiency rotation speed region of the motor has a range, and when the maximum efficiency rotation speed region exceeds the range, the efficiency of the motor is reduced sharply, and in most cases, the motor can only be designed according to a certain rotation speed with the longest working time in a working condition. In addition, the maximum speed of the conventional single-winding motor is often limited in order to take account of both the motor torque at low speed and the efficiency at low speed.
The low efficiency of the motor at low rotation speed is caused by comprehensive factors, and mainly has the following reasons:
1. various types of existing motors generate a magnetic field by passing current through a conductive coil, and the magnetic field and another magnetic field or a magnetic circuit generate acting force to generate torque to drive the motor to rotate.
The magnetic field strength H generated by the coil can be expressed by the following formula
H＝NC×In×ufe
N in the formulaCDenotes the number of turns of the coil, INRepresenting the current through the coil, u if there is a corefeWhich represents the permeability of the core. In the case where the permeability is a constant. The magnetic field strength is determined by the product of the current and the number of turns of the coil, i.e. the number of turns of ampere. Although the calculation formulas of the torque generated by the magnetic field strength H of various motors are different, the calculation formulas are proportional to the magnitude of H. The current flowing through the coil is limited by heat generation due to resistance, eddy current, and the like, and the current is also limited. The maximum torque of the electric machine is typically 3 to 6 times the rated torque. The torque is limited and the speed is low, which is the output power of the motor multiplied by the torque, resulting in low motor efficiency.
2. Electric machineAt lower speeds, self-induced electromotive force EφLower, and the supply voltage E of the motor's controller or frequency converterPIs substantially constant, the current I flowing through the motor coiln＝(EP-Eφ)/RfR in the formulafIs the equivalent impedance of the coil. Due to EφVery small, current I at this timeNThe motor can be very large, so the controller generally adopts a PWM (pulse-width modulation) mode to control the current, and the essential meaning is that intermittent stronger pulse current generates the same mechanical torque effect on the motor instead of continuous relatively weaker current. (although the current flowing in the coil is relatively continuous due to the inductive action of the coil and the freewheeling action of the power transistor of the controller, plus the PWM frequency, being sufficiently high, the portion of the energy that freewheels is also the pulse energy from the power supply). This way the result is that when EP-EφThe greater the voltage difference of (A), RfEquivalent resistance R of coilfThe smaller the PWM duty cycle, i.e. the shorter the time of the pulse, the higher the current value of the pulse. Besides a part of the energy of the current pulse is converted into effective mechanical work, the rest energy is converted into the following energy and is wasted:
a: the various mechanical and electromagnetic harmonics generated by the high energy pulses are dissipated as heat and radiation.
B: the larger the peak value of the current pulse, the higher the heat generation of the entire current loop, since the heat of the current on the resistor is converted to a square-times increase.
C: because the rotor of the motor is mechanical, the rotor has mass inertia, and according to the physical law, the intermittent energy pushing per se has lower transmission efficiency along with the smaller pulse time of the energy.
D: for a coil with a silicon steel sheet iron core, under the condition that current pulse exceeds a certain amplitude, a magnetic field can be saturated, and the rotation of current is wasted as heat energy on a resistor of the coil.
In order to widen the rotational speed range of the motor, the domestic inventors made many efforts and attempts. For example, the application numbers in the domestic patent documents are: 201510508099.0 entitled "permanent magnet synchronous machine winding switching device" and having application number: 201510508843.7 entitled "switching strategy based on permanent magnet synchronous machine winding switching device". Both patents mention a switching method of a permanent magnet synchronous motor, namely, a winding switching device of the permanent magnet synchronous motor is provided with n sets of windings, corresponds to n main loop units, and realizes the series-parallel switching of the n sets of windings through the combined action of 4n-4 switches. The windings are connected in series for operation, and if the rotating speed reaches a switching condition, the windings are switched from series connection to parallel connection; and the windings run in parallel, if the rotating speed reaches the switching condition, the voltage is reduced until the voltage switching condition is met, and the windings are switched from parallel connection to series connection. By adopting the technical scheme, the operation efficiency of the motor can be improved to a certain extent, the speed regulation range of the motor is expanded, and the requirement on the capacity of the main loop is reduced.
However, the above technical solutions have the following disadvantages:
1. n independent power sources are required to supply power, which is costly and complex in real-world applications. In particular, in a battery power supply system, a plurality of battery packs are used, which is a great trouble in both charging and battery management.
2. The battery pack needs to be switched in parallel by the switch, if the battery supplies power to a system, the voltage of the battery cannot be completely equal due to individual difference, the internal resistance of the battery is very small, and the switch is easily damaged due to very large impact current in the parallel connection process, so that the system is not reliable.
3. For the condition of windings with n larger than 2, the windings can only be in two states of all parallel connection or all serial connection, and have no intermediate transition state, so that the motor is unsmooth to switch. Under the condition of more n, because the windings are all connected in series, the induced electromotive forces of the windings are all added, and the speed range of the motor working in the full series connection is narrowed, the purpose of widening the rotating speed range of the motor cannot be realized.
Therefore, the present inventors have earnestly demanded to conceive a new technology to improve the problems thereof.
Disclosure of Invention
The invention aims to provide a switching device for the wide speed of a motor, which only needs to use an independent power supply, can multiply expand the high-efficiency rotating speed area of the motor, greatly improves the performance of the motor and improves the energy utilization rate.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a switching apparatus for a wide speed of a motor, comprising: the power supply comprises a power supply module, a series-parallel connection switching module and a PWM modulation and power driving module, wherein the series-parallel connection switching module comprises N switching units, each switching unit comprises a first switching switch, a second switching switch and a third switching switch, an S port of the first switching switch is connected with a negative electrode of the power supply module, and a D port of the first switching switch is connected with an S port of the second switching switch; a D port of the second change-over switch is connected with an S port of the third change-over switch, and a D port of the third change-over switch is connected with the positive pole of the power supply module; the PWM modulation and power driving module is respectively connected with the power supply module and the series-parallel switching module, wherein N is more than or equal to 1.
Preferably, the power supply further comprises a gate driving power supply module, wherein the gate driving power supply module comprises M output ends, and the output ends of the M output ends are connected with the series-parallel switching module and the PWM modulation and power driving module; wherein M is more than or equal to 1.
Preferably, the motor also comprises a current detection module and a symmetrical winding motor, wherein the input end of the current detection module is connected with the PWM modulation and power driving module, the output end of the current detection module is connected with the symmetrical winding motor, and a rotor position detector is arranged on the symmetrical winding motor.
Preferably, the current detection module includes a plurality of sampling resistors, one end of each sampling resistor is connected to the PWM modulation and power driving module and a signal amplifier, and the other end of each sampling resistor is connected to the negative electrode of the power supply module.
Preferably, the motor further comprises a signal processing and logic control module, which is respectively connected with the series-parallel switching module, the PWM modulation and power driving module, the current detection module and the rotor position detector of the symmetrical winding motor.
Preferably, the PWM modulation and power driving module includes a plurality of driving units, each driving unit includes an anode common terminal, a cathode common terminal and a gate driving power input terminal, and the anode common terminal is connected to the anode of the power supply module or the fourth port of a switching unit; the negative electrode common end is connected with the negative electrode of the power supply module or a third port of a switching unit; the input end of the grid driving power supply is connected with one output end of the grid driving power supply module. In the figure, reference numeral 1 denotes a first port, reference numeral 2 denotes a second port, reference numeral 3 denotes a third port, and reference numeral 4 denotes a fourth port.
Preferably, the driving unit is a full-bridge driving circuit or a multi-path half-bridge driving circuit.
Preferably, the first and/or second and/or third diverter switch is a mechanical contact switch or an electronic switch.
Preferably, the gate driving power module further comprises a first common terminal and a second common terminal, wherein the first common terminal is connected with the positive electrode of the power supply module, and the second common terminal is connected with the negative electrode of the power supply module.
Preferably, the gate driving power module further includes a first common terminal and a second common terminal, wherein the first common terminal and the second common terminal are connected to an external power source.
By adopting the technical scheme, the invention at least comprises the following beneficial effects:
the switching device for the wide speed of the motor only needs to use one independent power supply, has simple structure and lower cost, and does not damage a switch. And by controlling the on and off of the change-over switch in the series-parallel switching module, various series-parallel states can be realized, rather than the two states of pure all parallel connection or all series connection. Especially, under the condition of more windings of the motor, the high-efficiency rotating speed area of the motor can be multiplied, the performance of the motor is greatly improved, and the energy utilization rate is improved.
Drawings
FIG. 1 is a schematic diagram of a switching apparatus for a wide speed of a motor according to the present invention;
FIG. 2a is a schematic circuit diagram of the switching device for the wide speed of the motor according to the present invention;
FIG. 2b is a schematic circuit diagram of the switching device for the wide speed of the motor according to the present invention;
FIG. 3a is a schematic circuit diagram of a PWM modulation and power driving module according to the present invention;
FIG. 3b is a schematic circuit diagram of the PWM modulation and power driving module according to the present invention;
FIG. 4a is a schematic circuit diagram of a current detection module according to the present invention;
FIG. 4b is a schematic circuit diagram of the current detection module according to the present invention;
FIG. 4c is a schematic circuit diagram of the current detection module according to the present invention;
FIG. 5a is a schematic circuit diagram of a single transformer multi-way isolated voltage-stabilized power supply;
FIG. 5b is a schematic circuit diagram of a multi-transformer multi-way isolated voltage regulator;
FIGS. 6a-6c are schematic diagrams of equivalent circuits in a fully series state;
FIGS. 7a-7c are schematic diagrams of equivalent circuits in a fully parallel state;
FIGS. 8a-8c are schematic diagrams of equivalent circuits for the 2-and-2-series state;
fig. 9 is a handover flowchart.
Wherein: 1. the device comprises a power supply module, a signal processing and logic control module, a series-parallel connection switching module, a PWM (pulse width modulation) and power driving module, a grid driving power supply module, a current detection module, a symmetrical winding motor, a magnetic ring, a current Hall sensor, a rotor position detector and a motor control module, wherein the power supply module 2, the signal processing and logic control module, the series-parallel connection switching module, the PWM and power driving module, the grid driving power supply module 5, the current detection module 6.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1 to 2, a switching device for a wide speed of a motor according to the present invention includes: the power supply system comprises a power supply module 1, a series-parallel connection switching module 3 and a PWM modulation and power driving module 4, wherein the series-parallel connection switching module 3 comprises N switching units, each switching unit comprises a first switching switch PK (N), a second switching switch SK (N) and a third switching switch NK (N), wherein the S port of the first switching switch is connected with the negative electrode of the power supply module 1, and the D port of the first switching switch is connected with the S port of the second switching switch and a driving unit; and the D port of the second change-over switch is connected with the S port of the third change-over switch, and the D port of the third change-over switch is connected with the positive pole of the power supply module 1. The PWM modulation and power driving module 4 is respectively connected with the power supply module 1 and the series-parallel connection switching module 3, wherein N is more than or equal to 1.
In a preferred embodiment, as shown in fig. 2a, the system further includes a gate driving power module 5, wherein the gate driving power module 5 includes M output terminals, and the output terminals of the M output terminals are connected to the series-parallel switching module 3 and the PWM modulation and power driving module 4; wherein M.gtoreq.1, more preferably M ═ N + 1. In another preferred embodiment, as shown in fig. 2b, a gate power source is provided in each driving unit of the PWM modulation and power driving module 4.
Preferably, the motor further comprises a current detection module 6 and N +1 symmetrical winding motors 7, wherein the input end of the current detection module 6 is connected with the PWM modulation and power driving module 4, the output end of the current detection module is connected with the symmetrical winding motors 7, and the symmetrical winding motors are electronically provided with a rotor position detector 10. The symmetrical winding motor 7 is a variety of motors with multiple paths of parallel windings which are insulated electrically and have the same magnetic circuit. A specific embodiment of a symmetrical winding motor 7 is provided, as in patent application No. 201110385907.0 entitled "single machine multiple drive multiple winding motor system". Of course, the particular arrangement of the motor windings described above is intended to be illustrative of the present embodiment and not limiting, and any obvious variations and alterations are within the scope of the present embodiment.
Preferably, the current detection module 6 includes a plurality of sampling resistors, one end of each of the sampling resistors is connected to the PWM modulation and power driving module 4 and a signal amplifier, and the other end of each of the sampling resistors is connected to the negative electrode of the power supply module 1.
Preferably, the device further comprises a signal processing and logic control module 2, which is respectively connected with the series-parallel connection switching module 3, the PWM modulation and power driving module 4, the current detection module 6 and the rotor position detector 10 of the symmetrical winding motor 7. The control ends of the first change-over switch, the second change-over switch and the third change-over switch are all connected with the signal processing and logic control module 2 and act under the control of the signal processing and logic control module. Preferably, the signal processing and logic control module 2 is a single chip microcomputer including a motor speed sensor, a phase current sensor and a running motor control algorithm.
Preferably, the PWM modulation and power driving module 4 includes a plurality of driving units, each of the driving units includes a positive common terminal, a negative common terminal and a gate driving power input terminal, and the positive common terminal is connected to the positive terminal of the power supply module 1 or the fourth port of a switching unit; the negative electrode common end is connected with the negative electrode of the power supply module 1 or a third port of a switching unit; the input end of the gate driving power supply is connected with one output end of the gate driving power supply module 5. In the figure, reference numeral 1 denotes a first port, reference numeral 2 denotes a second port, reference numeral 3 denotes a third port, and reference numeral 4 denotes a fourth port.
Preferably, the driving unit is a full-bridge driving circuit or a multi-path half-bridge driving circuit.
Preferably, each of the driving units includes a gate driving port, and the gate driving port is connected to an output port of the gate driving power module 5. Because the output ports of the gate driving power supply module 5 are electrically isolated from each other, and the gate driving port of the PWM modulation and power driving module 4 is also electrically isolated, the gate driving power supply module 5 supplies power to the driving unit instead of using a power supply, so that a plurality of independent power supplies are not needed, the application cost is reduced, and problems caused by the use of a plurality of power supplies can be easily solved.
Preferably, the number of the driving units is N + 1. If each switching unit is numbered from 1 to N in sequence, and each driving unit is numbered from 1 to N +1 in sequence, the anode common end of the first driving unit is connected with the anode of the power supply module 1, the anode common end of the second driving unit is connected with the fourth port of the first switching unit, and so on, the anode common end of the (N + 1) th driving unit is connected with the fourth port of the Nth switching unit. The negative electrode common end of the first driving unit is connected with the negative electrode of the power supply module 1, the negative electrode common end of the second driving unit is connected with the third port of the first switching unit, and so on, the negative electrode common end of the (N + 1) th driving unit is connected with the third port of the Nth switching unit.
Preferably, the first and/or second and/or third diverter switch is a mechanical contact switch or an electronic switch. In a preferred embodiment, the first switch is one or more of a relay, a MOS transistor, and an insulated gate bipolar transistor; the second change-over switch is one or more of a diode, a relay, an MOS (metal oxide semiconductor) tube and an insulated gate bipolar transistor; the third change-over switch is one or more of a relay, an MOS (metal oxide semiconductor) tube and an insulated gate bipolar transistor.
Preferably, the gate driving power module 5 further includes a first common terminal and a second common terminal, wherein the first common terminal is connected to the positive electrode of the power supply module 1, and the second common terminal is connected to the negative electrode of the power supply module 1.
Preferably, the gate driving power module 5 further includes a first common terminal and a second common terminal, wherein the first common terminal and the second common terminal are connected to an external power source.
Preferably, the motor includes, but is not limited to, a brushless motor, a permanent magnet synchronous motor, an alternating current motor, a reluctance motor, a stepping motor, a linear motor. The whole system except the motor can be packaged by a wafer and integrated in a thick film integrated block, or integrated in a semiconductor chip, or distributed in a plurality of entities and interconnected by a wire. The present invention is not limited to the specific packaging method, and those skilled in the art will appreciate.
The principle of the invention is as follows: when the motor starts to run at a low speed, if a plurality of windings of the motor are equivalently connected in series, the current can be relatively reduced when the number of turns is increased according to the ampere-turn relation of the coil, although the fact that the efficiency of the motor when the motor stops rotating due to resistance torque is zero cannot be changed, the input power is reduced due to the reduction of the current, and the energy utilization efficiency of the whole motor system comprising a power supply, a controller and the motor is improved.
Also because of the relation of the series connection of the windings, the self-induced electromotive force EφIncrease, EP-EφThe value becomes smaller and the equivalent resistance R of the winding coil of the motor becomes smallerfWhen the pulse width modulation is increased, the pulse width modulation is adjusted to the same current effect by PWM, the duty ratio is increased, the pulse peak value of the current is reduced, and various losses are reduced. Along with the improvement of the utilization rate of the current, the heat productivity of the motor is reduced, and the torque of the motor can be properly increased on the basis of the parameters of the original motor.
When the rotating speed of the motor is limited to the rotating speed of the motor due to the increase of self-induced electromotive force along with the increase of the rotating speed of the motor, the plurality of windings are converted into a series-parallel mixed state again, and all the windings are converted into a parallel state until the motor reaches a certain speed.
By the method, the efficiency curve of the motor is widened, the maximum torque of the motor is improved, the heat productivity of the motor is reduced, and the endurance time of the battery is prolonged for a system taking the battery as an energy source.
In the conventional single-winding motor, the maximum speed is limited in order to achieve both the motor torque at a low speed and the efficiency at the low speed. When the multi-winding series-parallel connection mixing is used, the rotating speed range of the motor can be greatly expanded without losing the performance at low speed.
The invention is fully described below in a specific embodiment, but it will be appreciated by those skilled in the art that other obvious variations and modifications are within the scope of the invention.
In the preferred embodiment, the PWM modulation and power driving module 4 is composed of a full bridge or three half bridges and other general driving circuits. Fig. 3a and 3b provide two more common circuit forms. FIG. 3a is used to drive AC motors, brushless motors, etc.; fig. 3b is used to drive stepper motors, reluctance motors, etc. Wherein the gate drive supply (VCC) of each power circuit portion is isolated from each other. The input end and the output end of the grid driving signal are not in common ground, and the grid driving can be carried out by various isolation types, such as an A optical coupler type: such as HCPL-3120 from HP, FOD8384 from FAIRCHILD, etc.; b, magnetic isolation: such as ADuM6132 from ANALOG DEVICES, Inc.; c is not isolated but not co-located: such as IRS2117, IRS2118, of IR corporation.
As shown in fig. 4a and 4b, the current detection module 6 includes a plurality of magnetic rings 8, and the magnetic rings 8 are disposed between the PWM modulation and power driving module 4 and the symmetrical winding motor 7. All the wires of the same phase need to pass through the magnetic ring 8 from the same direction to correctly sample the real phase current. The current hall sensor 9 is located in the open gap of the magnetic ring 8 (preferably, the current hall sensor 9 can be a1363 from the company alegoro). Since all phase lines have the same current direction and phase, the currents are superimposed in the forward direction. When three-phase current is sampled, the calculation method comprises the following steps:
phase V current is equal to IV(1)+IV(2)+IV(3)+……+IV(N)；
Phase of U-phase current IU(1)+IU(2)+IU(3)+……+IU(N)；
Phase of W current is equal to IW(1)+IW(2)+IW(3)+……+IW(N)。
Of course, in order to save cost, only the currents of two phases may be sampled, and the current of the third phase may be calculated by the formula i (w) + i (u) + i (v) ═ 0. The current of only one of the windings may be sampled and multiplied by the number N of symmetrical windings. Those skilled in the art can select and set the parameters according to actual usage, which is not limited in this embodiment.
In another preferred embodiment, as shown in fig. 4c, the current detection module 6 includes a plurality of sampling resistors, one end of each sampling resistor is connected to the PWM modulation and power driving module 4 and a signal amplifier, the other end of each sampling resistor is connected to the negative electrode of the power supply module 1, and the signal amplifier is connected to the signal processing and logic control module 2. In low-cost application, current information can be obtained only by a sampling resistor at the last lower bridge driven by PWM modulation and power, and the current information is amplified to a certain extent and then enters ADC processing. The method is characterized in that current information can be really sampled under the condition of full series connection; in other combination states, the symmetrical windings have equal currents and can be multiplied by N, wherein N is the number of the symmetrical windings.
The grid driving power supply module 5 is one of a single-transformer multi-path isolation stabilized voltage supply or a multi-transformer multi-path isolation stabilized voltage supply. FIG. 5a shows a single transformer isolated regulated power supply, and FIG. 5b shows a multi-transformer isolated regulated power supply. Both include M outputs electrically isolated from each other, with the difference that the multi-transformer multi-isolation regulated power supply includes a plurality of independent PWM control units.
This embodiment can produce a variety of series-parallel states. The equivalent circuit as in its fully series state is shown in fig. 6a to 6 c; when the first switch and the third switch are turned off, the second switch is turned on due to the forward voltage drop, and the current flows as shown in fig. 6b and 6c, thereby forming a series connection. When all are connected in series, Eall＝E1+E2+E3+……+EN。
The equivalent circuits in their fully parallel state are shown in fig. 7a to 7 c. When the first switch and the third switch are turned on and the second switch is turned off, the current flows as shown in fig. 7b and 7c, and the parallel connection is formed. All-purposeWhen sections are connected in parallel, Eall＝E1＝E2＝E3……＝EN。
When N is 3, the equivalent circuit of 2 parallel-to-2 series is as shown in fig. 8a to 8 c. At the moment, the states of the change-over switches of the first driving unit and the third driving unit are consistent, the first change-over switch and the third change-over switch are closed, and the second change-over switch is opened; the second driving unit is opposite to the first driving unit. At this time Eall＝E1+E2＝E3+E4. Of course, if the value of N is larger, more different series-parallel states can be provided, that is, a transition state between the two states of all parallel states or all series states can be provided, so as to avoid unsmooth switching of the motor. For various different serial-parallel states, those skilled in the art can fully know based on the disclosure of the present embodiment, and the present embodiment is not described herein.
There are different strategies for the switching of the multiple windings in this embodiment, as follows:
1. the set gear is given manually.
2. Switching is performed according to the magnitude of the back electromotive force.
3. Switching is performed according to the rotation speed of the motor.
4. And switching according to the magnitude of the phase current of the motor.
Whatever the above switching manner (the above switching manner can be set by a person skilled in the art according to actual use conditions, and the present embodiment does not limit this), attention is paid to the voltage value of the back electromotive force E (n) generated by each winding of the motor during rotation, because when the windings of the motor are switched from parallel to series, the back electromotive forces generated by all the windings in series are added, so as to ensure the total back electromotive force E after switchingallAnd a supply voltage EPDo not differ much, E is detectedallWhen the voltage value reaches a proper value, the switching command from parallel connection to series connection can be executed.
Because each winding of the motor is symmetrical, the generated back electromotive force is basically the same, namely E (1) ═ E (2) ═ … … ═ E (N), only the voltage value of any one winding needs to be measured, wherein the negative pole common end P _ COM of the PWM modulation and power driving module (N) is always connected to the power supply ground wire, the voltage of the back electromotive force E (N) thereof is also referenced to the ground wire, and the detection is most convenient and the cost is low. And other windings are in suspension due to the change of series connection and parallel connection, and the measurement is carried out in an isolation mode.
When switching from series to parallel, this can be disregarded since there is no problem of back emf addition.
The switching process has a certain time delay no matter the relay or the semiconductor power tube is used as a change-over switch. In switching states, the switches are functionally divided into two types, 1: series switch SK, 2: and switches PK and NK are connected in parallel. The two types of switches can not act simultaneously to prevent the short circuit of the anode and the cathode of the power supply.
When switching, a delay time is waited, and after one type of switch which is opened originally is completely closed, the other type of switch can be opened. The same type of switch can be opened and closed simultaneously without considering the problem of switching delay, the delay time value is properly adjusted according to different switches, the relay is generally within 200ms, and the IGBT or the MOSFET is generally within the range of 100us to 50ns due to different gate driving currents. The value of delay requires actual measurement or calculation from parameters if the optimum switching speed is to be achieved.
In the following, the series-parallel state is switched according to the speed and the back electromotive force by comprehensively judging n is 3, and fig. 9 illustrates a switching process in a flowchart.
Under the condition that the windings and the PWM modulation and power driving module change the series-parallel connection relationship, all the windings are symmetrical and controlled by the same set of PWM signals, after the series-parallel connection relationship of the windings is changed, only the equivalent turns of the windings and the torque value under the same phase current are changed, and after the series-parallel connection state is converted, the following conditions are provided for different motors:
1. motors without open-loop control of the current loop, such as Alternating Current Motors (ACM) of the V/F control type and brushless motors (BLDC) without the current loop, have no effect on the control algorithm after changing the equivalent series-parallel relationship of the windings, but may generate a certain amount of torque ripple.
2. For motors with current loop control algorithm, such as Permanent Magnet Synchronous Motor (PMSM) and AC motor with FOC algorithm, based on original control algorithm, according to current series-parallel connection state, current reference value I given from speed PID loop or directlyrefAnd modifying by using a group of corresponding coefficients while changing the serial-parallel state of the winding.
For motors, the essential result of phase current control is motor torque control, and different motors, different current and torque calculation formulas may be different and may be non-linear. If the motor is a brushless motor or a permanent magnet synchronous motor, the current torque curve is approximate to linearity due to the characteristic of the motor which is close to the DC brush motor, and K can be directly taken according to the series-parallel multiple relationiThe values of (a) are as follows:
when fully connected in parallel, Ki＝1；
When two are in parallel and two are in series, Ki＝2；
When all strings are present, Ki＝4；
Iref＝Iref*Ki(ii) a (self-assignment expression of language C)
Modified IrefAnd then entering the next step of inverse PARK conversion.
3. The method comprises the steps of controlling a brushless Hall-free motor and a permanent magnet synchronous motor which need motor parameters, controlling an alternating current FOC without an encoder, wherein the commonly used motor parameters comprise phase inductance, phase resistance and induced electromotive force, and after series-parallel connection switching, the parameters on a winding are changed into integral multiples after the algorithm for Hall-free operation needs to be calculated. The algorithm for correcting the coefficients will be known to those skilled in the art and will not be described in detail herein.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A switching device for a wide speed of an electric motor, comprising: the power supply comprises a power supply module, a series-parallel connection switching module and a PWM modulation and power driving module, wherein the series-parallel connection switching module comprises N switching units, each switching unit comprises a first switching switch, a second switching switch and a third switching switch, an S port of the first switching switch is connected with a negative electrode of the power supply module, and a D port of the first switching switch is connected with an S port of the second switching switch; a D port of the second change-over switch is connected with an S port of the third change-over switch, and a D port of the third change-over switch is connected with the positive pole of the power supply module; the D port of the third switch forms a first port, the S port of the first switch forms a second port, the D port of the first switch and the S port of the second switch form a third port, and the D port of the second switch and the S port of the third switch form a fourth port; the PWM modulation and power driving module is respectively connected with the power supply module and the series-parallel switching module, wherein N is more than or equal to 1;
the grid driving power supply module comprises M paths of output ends, the output ends of the M paths of output ends are connected with the series-parallel switching module and the PWM modulation and power driving module, and the PWM modulation and power driving module comprises N +1 driving units; wherein M is more than or equal to 1.
2. The switching apparatus for a motor broadspeed of claim 1, wherein: the PWM and power driving circuit is characterized by further comprising a current detection module and a symmetrical winding motor, wherein the input end of the current detection module is connected with the PWM modulation and power driving module, the output end of the current detection module is connected with the symmetrical winding motor, and a rotor position detector is arranged on the symmetrical winding motor.
3. The switching apparatus for a motor broadspeed of claim 2, wherein: the current detection module comprises a plurality of sampling resistors, one end of each sampling resistor is connected with the PWM modulation and power driving module and the signal amplifier, and the other end of each sampling resistor is connected with the negative electrode of the power supply module.
4. The switching apparatus for a motor broadspeed of claim 3, wherein: the system also comprises a signal processing and logic control module which is respectively connected with the series-parallel connection switching module, the PWM modulation and power driving module, the current detection module and a rotor position detector of the symmetrical winding motor.
5. The switching apparatus for a wide speed of a motor according to any one of claims 1 to 4, wherein: each driving unit comprises an anode common end, a cathode common end and a grid driving power supply input end, wherein the anode common end is connected with the anode of the power supply module or the fourth port of a switching unit; the negative electrode common end is connected with the negative electrode of the power supply module or a third port of a switching unit; the input end of the grid driving power supply is connected with one output end of the grid driving power supply module.
6. The switching apparatus for a motor broadspeed of claim 5, wherein: the driving unit is a full-bridge driving circuit or a multi-path half-bridge driving circuit.
7. The switching apparatus for a motor broadspeed of claim 6, wherein: the first change-over switch and/or the second change-over switch and/or the third change-over switch are mechanical contact switches or electronic switches.
8. The switching apparatus for a motor broadspeed of claim 7, wherein: the grid driving power supply module further comprises a first public end and a second public end, wherein the first public end is connected with the anode of the power supply module, and the second public end is connected with the cathode of the power supply module.
9. The switching apparatus for a motor broadspeed of claim 7, wherein: the grid driving power supply module further comprises a first common end and a second common end, wherein the first common end and the second common end are connected with an external power supply.
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| CN101895142A (en) * | 2010-06-22 | 2010-11-24 | 海尔集团公司 | Generator-based charging circuit for charging energy storage component |
| CN104953743A (en) * | 2014-03-27 | 2015-09-30 | 陈意辉 | Electronic multi-gear variable-speed motor of electric vehicle and control system thereof |
| CN105048925A (en) * | 2015-08-18 | 2015-11-11 | 重庆大学 | Switching strategy based on switching device of permanent magnet synchronous motor windings |
| CN206259879U (en) * | 2016-10-14 | 2017-06-16 | 江先武 | A kind of switching device for motor speed wide |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE102007040725A1 (en) * | 2007-08-29 | 2009-03-05 | Robert Bosch Gmbh | Electric machine |
| CN105048900B (en) * | 2015-06-23 | 2017-11-03 | 西北工业大学 | Double winding brshless DC motor frequency multiplication control circuit of chopping and winding switching method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101895142A (en) * | 2010-06-22 | 2010-11-24 | 海尔集团公司 | Generator-based charging circuit for charging energy storage component |
| CN104953743A (en) * | 2014-03-27 | 2015-09-30 | 陈意辉 | Electronic multi-gear variable-speed motor of electric vehicle and control system thereof |
| CN105048925A (en) * | 2015-08-18 | 2015-11-11 | 重庆大学 | Switching strategy based on switching device of permanent magnet synchronous motor windings |
| CN206259879U (en) * | 2016-10-14 | 2017-06-16 | 江先武 | A kind of switching device for motor speed wide |
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