TWI514747B - Switched reluctance motor controller and control method thereof - Google Patents

Description

Switched reluctance motor control device and control method thereof

The present invention relates to a switched reluctance motor, and more particularly to a control method for reducing the copper loss of a stator coil by controlling the waveforms of the excitation and demagnetization currents of the switched reluctance motor.

In the prior art, the switched reluctance motor causes a loss of efficiency, and there are damages such as copper loss, damage and mechanical damage. The copper loss is caused by the coil resistance and the excitation current, and the loss is switched. The magnetic field is generated, and the mechanical damage is caused by the frictional force of the rotor bearing connecting motor when rotating.

FIG. 1 is a schematic diagram showing coil inductance values corresponding to rotor angles of two phases of a conventional switched reluctance motor. In Fig. 1, the solid line is the outgoing phase, that is, the phase adjacent to the two phases overlapping the demagnetization, and the dotted line is the entering phase, that is, the adjacent two phases overlap and are excited. In the interval of 1-1/1-2, when the phase of the outgoing phase/incoming phase is the lowest, the differential of the inductance to the rotor angle is zero. At this time, there is no reaction electromotive force, and the rise time of the excitation current can be short, but no rotation occurs. Moment. In the interval 1-3/1-4, it is the outgoing phase/into the phase inductor rising region. At this time, the inductance is proportional to the rotor angle by a positive slope. The rise time of the exciting current is due to the existence of the reactive electromotive force. The current is proportional to the positive torque and the optimal range of excitation. In the interval 1-5/1-6, when the outgoing phase/input phase inductance value is the highest, The differential of the inductance to the rotor angle is zero, and the rise time of the excitation current is longer than the interval of 1-1/1-2. Because the inductance is relatively large, no torque is generated in this interval, and the current is not allowed to conduct in this interval. In the range of 1-7/1-8, it is the outgoing phase/into the phase inductance drop region. Under this ideal condition, the inductance of the inductor is slightly divided into a negative slope. The excitation current will generate a negative torque in this interval. The interval produces current.

As can be seen from the above description, the switched reluctance motor has a two-phase overlapping rising inductance region due to the structural relationship, and this overlapping rising inductance region is liable to cause unnecessary copper loss.

An object of the present invention is to provide a switched reluctance motor control device and a control method thereof for effectively controlling the excitation and demagnetization current waveforms, which can reduce the copper loss of the stator coil of the switched reluctance motor and can improve Overall efficiency.

The invention provides a switched reluctance motor control device, wherein the switched reluctance motor control device comprises a feedback current acquisition unit, a control unit, a pulse width control current unit and an asymmetric half bridge inverter. The feedback current obtaining unit is coupled to the motor to obtain the outgoing phase current and the incoming phase current. The control unit is coupled to the feedback current obtaining unit to process the outgoing phase current and the incoming phase current, so that the exciting current entering the phase current starts at a first corner (a corner where the inductor is about to rise) and a second corner (the inductor reaches a maximum value) Between the corners, the end of the current of the outgoing phase current ends no later than the second corner, and the exciting current entering the phase current ends at the end of the current of the outgoing phase current. The pulse width control current unit is coupled to the control unit to receive the processed outgoing phase current and the processed incoming phase current to generate a driving signal. The asymmetric half-bridge inverter is coupled to the pulse width control current unit and the motor to control the operation of the motor according to the driving signal.

In an embodiment of the invention, if the control unit detects the end of the current flowing out of the phase current After the end ends at the second corner, the control unit controls the phase current to be removed such that the current end does not exceed the second corner.

In an embodiment of the invention, the control device controls the excitation current lead angle of the incoming phase current such that the excitation current entering the phase current begins before the demagnetization current of the outgoing phase current begins to occur.

In an embodiment of the invention, the control device controls the excitation current of the outgoing phase current to begin at or before the first corner.

In an embodiment of the invention, the excitation current entering the phase current begins with a certain current of the outgoing phase current being converted to a rotation angle corresponding to a demagnetization current.

The invention further provides a control method for a switched reluctance motor control device, comprising: (a) obtaining an outgoing phase current and an incoming phase current; (b) determining an angle corresponding to an outgoing phase current and a related current component of the incoming phase current, To provide an angle control result; (c) calculate a total effective current according to the outgoing phase current and the incoming phase current; and (d) perform current distribution processing according to the total effective current, speed loop related current and angle control results, so as to enter the phase The excitation current of the current starts between the first rotation angle and the second rotation angle, and the current end of the outgoing phase current ends no later than the second rotation angle, and the excitation current entering the phase current ends at the end of the current of the outgoing phase current.

In an embodiment of the invention, in the step (b) and the step (d), if the current end of the phase current is detected to end after the second corner, the current end of the phase current is adjusted to make the current end of the phase current It is controlled not to exceed the second corner.

In an embodiment of the invention, wherein in step (d), the excitation current entering the phase current is controlled by the first rotation angle or the advance conduction angle, so that the excitation current entering the phase current starts from the demagnetization current of the outgoing phase current. Before starting to produce.

In an embodiment of the invention, wherein in step (d), the exciting current of the outgoing phase current is controlled to start at or before the first corner.

In an embodiment of the invention, wherein in step (d), the excitation current entering the phase current is controlled to start at a rotation angle corresponding to a certain current of the outgoing phase current to a demagnetization current.

Based on the above, the switched reluctance motor control device and the control method thereof of the present invention adopt external loop speed control and inner loop current control, and use current control to indirectly control torque so that current control of the two-phase overlapping rising inductance region can be satisfied. The required torque minimizes the integration of the current in the overlap region and reduces the copper loss to improve efficiency.

Therefore, the advantages and spirit of the present invention can be further understood from the following detailed description of the invention and the accompanying drawings.

2-0‧‧‧Control unit

2-1‧‧‧Efficient current estimation unit

2-2‧‧‧ Current distribution unit

2-3‧‧‧Angle control unit

2-4‧‧‧ Pulse width control current unit

2-5‧‧‧Asymmetric half-bridge inverter

2-6‧‧‧Motor

2-7‧‧‧Responsive current acquisition unit

2-9‧‧‧PI controller

2-10‧‧‧Angular differentiator

3-1‧‧‧Angle difference unit

3-2‧‧‧ Current end detector

5-3,5-6,6-6‧‧‧Excitation current

5-4,5-5‧‧‧Constant current

5-8.5-7‧‧‧Demagnetization current

5-9‧‧‧ Control points

5-10‧‧‧Overlapping interval

1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8‧‧

S405~S425‧‧‧Steps

The following drawings are a part of the specification of the invention, and are in the

FIG. 1 is a schematic diagram showing coil inductance values corresponding to rotor angles of two phases of a conventional switched reluctance motor.

FIG. 2 is a functional block diagram of the switched reluctance motor device of the present invention.

FIG. 3 is a block diagram showing the internal function of the advanced angle control unit according to an embodiment of the invention.

FIG. 4 is a flow chart showing a method for controlling current distribution of two phases overlapping according to an embodiment of the present invention.

Figure 5 is a schematic diagram showing current versus inductance values and resulting fixed torque output in accordance with one embodiment of the present invention.

FIG. 6 is a schematic diagram showing the current versus inductance values of another embodiment of the present invention and the behavior of currents under two different time conditions.

Reference will now be made in detail to the exemplary embodiments embodiments In addition, the same or similar elements or components are used in the drawings and the embodiments to represent the same or similar parts. In the following embodiments, when the component is referred to as being "connected" or "coupled" to another component, it can be electrically connected, connected between data or signal, directly connected or coupled to another An element, or there may be an element in between.

The invention relates to a switched reluctance motor control device and is coupled to a motor. FIG. 2 is a functional block diagram of the switched reluctance motor device of the present invention. In FIG. 2, the switched reluctance motor device includes a motor 2-6, an asymmetric half-bridge inverter 2-5, a pulse width control current unit 2-4, a feedback current obtaining unit 2-7, and a control unit 2 -0, PI controller 2-9 and angle differentiator 2-10, wherein control unit 2-0 further comprises an active current estimation unit 2-1, a current distribution unit 2-2 and an angle control unit 2-3.

In the present embodiment, the motor 2-6 of the above Fig. 2 is a reluctance type motor. The motors 2-6 are coupled to the asymmetric half-bridge inverter 2-5 and the feedback current obtaining unit 2-7, respectively. The feedback current obtaining unit 2-7 is further coupled to the control unit 2-0 and the angle differentiator 2-10. The control unit 2-0 is coupled to the feedback current obtaining unit 2-7 and the pulse width control current unit 2-4. .

In the second embodiment of the present embodiment, the effective current estimating unit 2-1, the current distributing unit 2-2 and the angle controlling unit 2-3, the PI controller 2-9, and the angle differentiator 2 in the control unit 2-0 -10 can be implemented using software, but the invention is not limited to being implemented in software.

In FIG. 2, the feedback current acquisition unit 2-7 may include a Hall sensor, an analog/digital converter, and a rotary encoder. In the present embodiment, the feedback current obtaining unit 2-7 can be implemented by hardware. The above Hall sensor can be used to sense the instantaneous current value of the motor 2-6, rotating The encoder can be used to measure the rotor position. The instantaneous current value on the amount side includes the outgoing phase current and the incoming phase current, and the outgoing phase current and the incoming phase current also pass through the analog/digital converter of the feedback current obtaining unit 2-7. After the conversion, it is transferred to the control unit 2-0.

Further, in Fig. 2, the present embodiment employs external loop speed control and inner loop current control to control the indirect control torque using current control, the control of the switched reluctance motor. In the outer loop speed control, the rotor position measured by the rotary encoder is transmitted to the angle differentiator 2-10 for differentiation to obtain a motor speed information. Then, a preset speed command is further provided to perform a first operation process on the preset speed command and the motor speed information to obtain a speed difference. Then, a predetermined current is generated through the PI controller 2-9.

The inner loop current control of Fig. 2 as described above is achieved by the effective current estimating unit 2-1, the current distributing unit 2-2, and the angle controlling unit 2-3. The angle control unit 2-3 performs an optimized angle control process. The control mechanism mainly controls the advance conduction angle. In a low speed condition, the advance conduction angle is not controlled, and the advance conduction angle does not exceed θ. _1. For details, please refer to it later. The effective current estimating unit 2-1 mainly detects whether the measured outgoing phase current and the incoming phase current are effective currents. In the embodiment, the effective current represents a current capable of providing a torque force, and a description thereof is as follows. Details are detailed later. The current distribution unit 2-2 is configured to perform Current Sharing Control (CSC), which converts the speed difference into a reference current value, and then uses the CSC to divide the current into the phase current and the outgoing phase current.

The pulse width control current unit 2-4 of the above FIG. 2 is configured to receive the processed out phase current and the processed incoming phase current to generate a driving signal, for example, in the embodiment, driving The signal is a current driven signal. The above asymmetric half-bridge inverter is used to control the operation of the motor 2-6 according to the driving signal.

FIG. 3 is a block diagram showing the internal function of the angle control unit 2-3 according to an embodiment of the invention. In FIG. 3, the angle control unit 2-3 includes an angle difference operation unit 3-1 and a current end detector 3-2. The angle difference operation unit 3-1 is configured to perform an operation on the angle of the end current (Current Tail) and the second preset angle θ ₂ to obtain an angle difference. The mechanism is mainly used to limit the phase current. The angle ( θ _q ) of the current end of the demagnetizing current does not exceed the second predetermined angle ( θ ₂ ).

FIG. 4 is a flow chart showing a control method according to an embodiment of the present invention. FIG. 5 is a schematic diagram showing current versus inductance values according to an embodiment of the present invention. For the description of Fig. 4, please refer to Fig. 2 and Fig. 5 together. In step S405, the outgoing phase current and the incoming phase current are obtained by the feedback current obtaining unit 2-7, wherein the outgoing phase current and the incoming phase current are instantaneous current values of two adjacent phases.

In step S410 of FIG. 4, the angle control unit 2-3 of the control unit 2-0 determines whether the angle related to the two-phase current is in the first direction in accordance with the angle information provided by the encoder of the feedback current obtaining unit 2-7. A predetermined angle θ ₁ (the angle at which the inductance is about to rise) is between the second predetermined angle θ ₂ (the angle at which the inductance reaches the maximum value).

Please refer to FIG. 5, in this embodiment, control unit 2-0. Processing the outgoing phase current and the incoming phase current such that the excitation current 5-6 entering the phase current starts at a first predetermined angle θ ₁ (the angle at which the inductance is about to rise) and a second predetermined angle θ ₂ (the inductance reaches the maximum value) The corner), the current end 5-8 of the outgoing phase current ends no later than the second predetermined angle θ ₂ , and the exciting current 5-6 entering the phase current ends at the current end 5-8 of the outgoing phase current. In addition, the exciting current 5-8 entering the phase current is controlled at the first predetermined angle θ ₁ or the leading angle, so that the exciting current 5-6 entering the phase current starts to generate the demagnetizing current 5-8 of the outgoing phase current. prior to. In addition, the 5-8 exciting current of the outgoing phase current is controlled to start at or before the first predetermined angle θ ₁ .

In other words (refer to the embodiment of FIG. 5), the outgoing phase current includes an exciting current of 5-3, a constant current of 5-4, and a demagnetizing current of 5-8, wherein the opening phase of the outgoing phase current is 5-2 (Turn on angle) That is, at the first predetermined angle θ ₁ , that is, the excitation current of the outgoing phase current is caused by the first predetermined angle θ ₁ , and the constant current 5-4 can maintain the constant torque. In Fig. 5, the control point 5-9 is the second preset angle θ ₂ , and the control point 5-9 is used to limit the current end θ _{q of the} outgoing phase current not to exceed θ ₂ . The overlapping interval 5-10 is a two-phase overlapping current control such that a fixed current (torque) is generated and is equal to a phase-generated torque. In addition, the incoming phase current includes an excitation current 5-6, a constant current 5-5, and a demagnetization current 5-7, wherein the opening angle of the incoming phase current is controlled by the angle control unit 2-3 at the first predetermined angle θ ₁ and Between the two preset angles θ ₂ , that is, the excitation current 5-6 entering the phase current is controlled to start at a constant current of 5-4 of the outgoing phase current to a rotation angle corresponding to the demagnetization current 5-8, that is, The exciting current 5-6 entering the phase current begins between the first predetermined angle θ ₁ and the second predetermined angle θ ₂ . Further, the angle control unit 2-3 controls the time at which the exciting current 5-6 entering the phase current ends at the current end θ _q of the outgoing phase current.

In Fig. 5 of the embodiment, the corresponding angle θ _q of the current end of the outgoing phase current ends before the second predetermined angle θ ₂ . In the present embodiment, the angle control unit 2-3 determines whether the phase-out current is less than zero to determine the corresponding angle θ _q of the current end of the phase-out current. Then, the angle difference between the corresponding angle θ _q of the current end of the outgoing phase current and the second predetermined angle θ ₂ is used to determine whether the corresponding angle θ _q of the current end of the outgoing phase current exceeds the second preset. Angle θ ₂ , if the corresponding angle θ _q of the current end of the outgoing phase current exceeds the second predetermined angle θ ₂ , the angle control unit 2-3 controls the advance conduction angle of the incoming phase current so that the current end of the outgoing phase current The corresponding angle θ _q does not exceed (ends with) the second predetermined angle θ ₂ , that is, the angle control unit 2-3 causes the current end of the outgoing phase current to end no later than the second predetermined angle θ ₂ .

In step S415 of FIG. 4, the effective current estimating unit 2-1 calculates the effective current value of the sum of the two-phase currents by using the outgoing phase current, the incoming phase current, and the angle information provided by the feedback current obtaining unit 2-7. The formula can be referred to as follows:

In step S420 of FIG. 4, the current distribution unit 2-2 performs an operation according to the preset current provided by the PI controller 2-9 and the total effective current supplied by the effective current estimating unit 2-1 to generate A total reference current. Then, in step S425, the current distribution unit 2-2 preferentially allocates the maximum reference current to the incoming phase current, and then distributes the reference current to give the outgoing phase current, so that .

FIG. 6 is a schematic diagram showing current versus inductance values according to another embodiment of the present invention. Figure 6 is similar to Figure 5, except that Figure 6 assumes two conditions: 1. When t _overtap t _r When t _f is out, the phase current must not exceed the second preset angle θ ₂ , and the beginning of the phase current must fall at the first preset angle θ ₁ , so that the current distribution control is optimized; the second when t _overtap < t _r At t _f , since the current of the outgoing phase is likely to exceed the second predetermined angle θ ₂ , the phase current must be controlled so that the end of the outgoing phase current is controlled at the second predetermined angle θ ₂ . That is, the angle control unit 2-3 judges that the corresponding angle θ _q of the current end of the outgoing phase current exceeds the second predetermined angle θ ₂ , so the angle control unit 2-3 controls the phase current to enter the phase current. The corresponding angle θ _{q of the} end of the current ends at the second predetermined angle θ ₂ . At this time, the angle control unit 2-3 also controls the excitation current 6-6 entering the phase current to be controlled to advance the lead angle so that the excitation of the phase current is entered. The current begins before the demagnetization current of the outgoing phase current begins to be generated, and the exciting current that controls the outgoing phase current is controlled to start before the first predetermined angle θ ₁ .

In summary, the switching reluctance motor control device and the control method thereof according to the present invention, based on the consideration of copper loss, add some restrictions on the control angle strategy, so as to reduce the generation of unnecessary copper loss, so as to improve the switching magnetic Resistance motor efficiency. In addition, in the excitation phase, the purpose of the advance conduction angle is to excite the magnet when there is no reactive electromotive force, so that the current can rise rapidly, but this control of the conduction angle causes an additional copper loss that does not generate torque.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the present invention should be included in the following. Within the scope of the patent application.

S405~S425‧‧‧Steps

Claims (10)

A switching reluctance motor control device coupled to a motor, the switching reluctance motor control device comprising: a feedback current obtaining unit coupled to the motor to obtain an outgoing phase current and an incoming phase current; a unit coupled to the feedback current obtaining unit to process the outgoing phase current and the incoming phase current such that an exciting current of the incoming phase current begins between a first corner and a second corner, the outgoing phase current End of a current is not later than the second corner, and the exciting current of the incoming phase current ends at the end of the current of the outgoing phase current; a pulse width control current unit coupled to the control unit, Receiving the processed out phase current and the processed incoming phase current to generate a driving signal; and an asymmetric half bridge inverter coupled to the pulse width controlling current unit and the motor to be driven according to the driving A signal is used to control the operation of the motor. The switching reluctance motor control device according to claim 1, wherein the control unit controls the outgoing phase current if the control unit detects that the current end of the outgoing phase current ends after the second rotation angle The current end of the outgoing phase current does not exceed the second corner. The switching reluctance motor control device according to claim 2, wherein the control unit controls the excitation current lead angle of the incoming phase current, so that the excitation current of the incoming phase current starts from the outgoing phase current A de-magnetic current begins to occur before it begins. The switching reluctance motor control device according to claim 2, wherein the control unit The exciting current that controls the outgoing phase current begins at or before the first corner. The switching reluctance motor control device according to claim 1, wherein the excitation current of the phase current is started at a rotation angle corresponding to a depolarization current of the current of the phase current. A control method for a switched reluctance motor control device, comprising: (a) obtaining an outgoing phase current and an incoming phase current; (b) determining an angle corresponding to the outgoing current of the outgoing phase current and the associated current component of the incoming phase current, To provide an angle control result; (c) calculating a total effective current according to the outgoing phase current and the incoming phase current; and (d) performing a current according to the total effective current, a speed loop related current, and the angle control result Distributing processing such that an exciting current of the incoming phase current begins between a first corner and a second corner, a current end of the outgoing phase current ends no later than the second corner, and the phase current enters The exciting current ends at the end of the current of the outgoing phase current. The control method of claim 1, wherein in the step (b) and the step (d), if the current end of the outgoing phase current is detected to end after the second corner, the entering phase is adjusted. The current causes the current end of the outgoing phase current to be controlled not to exceed the second corner. The control method of claim 7, wherein in the step (d), the excitation current of the incoming phase current is controlled by the first turn or the lead angle, so that the excitation of the incoming phase current The current begins before a demagnetization current of the outgoing phase current begins to occur. The control method of claim 7, wherein in step (d), the exciting current of the outgoing phase current is controlled to start at or before the first corner. The control method of claim 6, wherein in step (d), the phase current is entered The exciting current is controlled to start at a rotation angle corresponding to a certain current of the outgoing phase current to a demagnetizing current.