Existing switched reluctance motor (being called SRM hereinafter) has stator 2 shown in Fig. 1 and rotor 4, wherein on stator 2+A level-A level ,+the B level and-the B level and+the C level and-the C level twined by A phase coil (LA), B phase coil (LB) and C phase coil (LC) respectively.
As shown in Figure 2, the drive circuit of the SRM of Gou Chenging has the smmothing capacitor (c) that is used to produce the direct current dc voltage like this, is used for voltage is offered coil (LA, LB, six switch element (QA+ LC), QA-, QB+, QB-, QC+, and six diodes (DA1, DA2, DB1 QC-),, DB2, DC1, DC2), it is used for being provided for coil (LA at voltage, LB LC) afterwards, returns at each switch element (QA+, QA-, QB+, QB-, QC+, the back electromotive force that produces when QC-) ending.
At this moment, be used to produce the switch element (QA+ that control A goes up mutually, the equipment of signal QA-), as shown in Figure 3, comprise the oscillator 12 that is used to produce pulse-width modulation (PWM) signal, and AND gate 16, its A that is used for being positioned at stator 2 when pulse-width signal that is produced by oscillator 12 and rotor 4 is mutually during magnetic level place, from the rotor-position signal of A phase position transducer 14 output and this pulse-width signal mutually " with ", and export its result, wherein when the signal from 14 outputs of A phase position transducer is imported into down the gate terminal of switch element (QA-), be imported into the gate terminal of switch element (QA+) from the signal of AND gate 16 outputs.
In other words, as shown in Figure 4, for the A to described SRM powers mutually, when signal is provided for switch element (QA+, QA-) gate terminal is when encouraging this switch element, and electric current (i) flows in the A of stator 2 phase coil (LA), thus magnetization stator 2+the A level and-the A level, produce repulsion like this and promote near the rotor 4 of magnetized A phase magnetic pole, thereby make rotor 4 rotations.
In like manner, electric current mode identical with A phase coil (LA) in B phase coil (LB) and C phase coil (LC) flows, and stator 2 is by according to A phase, B phase and C order magnetization mutually, thereby makes rotor 4 rotations, and SRM keeps rotating like this.
But, in described conventional SRM, have problems, as shown in Figure 4, as switch element (QA+, produce radial load when QA-) ending, feasible upward switch element (QA+) and following switch element (QA-) all end simultaneously, thereby at switch element (QA+, produce bigger radial load when QA-) being failure to actuate, and increase the big noise that causes owing to radial load.
Present invention is directed at and address the above problem, an object of the present invention is to provide a kind of being applicable to and reduce the radial load that when switched reluctance motor is driven, produces, thereby reduce the noise of switched reluctance motor.
According to this purpose of the present invention, provide a kind of switched reluctance motor (SRM) drive unit at this, this device comprises:
Position detection unit is used for the position of detection rotor when SRM is driven;
Inverter is used for providing electric energy to drive SRM according to the switching manipulation of switch element; And
Control unit, be used for merging in the scheduled time after the switch element closure from the rotor-position signal of position detection unit output and spontaneous pulse-width signal, with the signal of switch element output, and output is as the pulse-width signal with predetermined work cycle of the signal of switch element.
According to another aspect of the present invention, provide a kind of switched reluctance motor (SRM) drive unit at this, this device comprises:
Position detection unit is used for the position of detection rotor when switched reluctance motor is driven;
Inverter is used for providing voltage with the driving switch reluctance motor according to the switching manipulation of switch element; And
Control unit is used to merge rotor-position signal and spontaneous pulse-width signal, with the pulse-width signal with the work period of gradually reducing of output as the signal of switch element.
In order to understand essence of the present invention and purpose more fully, below as a result accompanying drawing specifically describe, wherein:
At this, specifically describe the preferred embodiments of the present invention with reference to the accompanying drawings.
Fig. 5 is the schematic block diagram that is used to illustrate driver for switching reluctance motor of the present invention, and Fig. 6 is the inverter in the switched reluctance motor drive circuit of the present invention and the block diagram of current detecting unit, wherein comprises key-press input unit 30, position detection unit 40, current detecting unit 50, inverter 60 and control unit 70 according to switched reluctance motor of the present invention (SRM) drive unit.
Key-press input unit 30 is used for being used for selecting whether to start SRM 20 to the control unit 70 input start up command signals and the signal of ceasing and desisting order.
When SRM 20 is driven, position detection unit 40 detection rotor positions, thereby rotor-position is input to control unit 70, and current detecting unit 50 detects in SRM 20 electric current that flows in the course of work of SRM 20, and it is input to control unit 70.
Inverter 60 is according to the signal console switch element of output from control unit 70, voltage being offered SRM 20, thereby drives SRM 20.
Inverter 60 comprises at this moment, as shown in Figure 6, comprises the smmothing capacitor (C) that is used to produce the direct current dc voltage, is used for voltage is offered coil (LA, LB, LC) six switch elements (QA+, QA-, QB+, QB-, QC+, and six diodes (DA1, DA2, DB1 QC-),, DB2, DC1, DC2), it is used for being provided for coil (LA at voltage, LB LC) afterwards, returns at each switch element (QA+, QA-, QB+, QB-, QC+, the back electromotive force that produces when QC-) ending.
In addition, as shown in Figure 6, current detecting unit 50 has and is used at A phase switch element (QA+, QA-) detect first of electric current during conducting and detect resistance R S1, be used at A phase switch element (QA+, detect second of electric current when QA-) ending and detect resistance R S2, be used for difference and amplify the differential amplifier (operational amplifier) of the current value that is detected by first and second detection resistance R S1 and the RS2, and be used for regulating resistance (R1 from the current value of differential amplifier (operational amplifier) output, R2, R3, R4).
Simultaneously, control unit 70 is according to determining the work period from the sensed current signal of current detecting unit 50 outputs, to produce pwm signal, and pwm signal is merged mutually with the rotor-position signal of exporting from position detection unit 40, be used for switch element (QA+, QA-with output, QB+, QB-, QC+, QC-) carry out the signal of switching manipulation, at switch element (QA+, QA-, QB+, QB-, QC+, QC-) end after, control unit 70 output has the pwm signal in predetermined work cycle as switch element (QA+, QA-, QB+, QB-, QC+, QC-) signal, and keep preset time.
In addition, in the SRM drive unit according to second embodiment of the invention, control unit 70 outputs have the pwm signal of the work period that reduces gradually as switch element (QA+, QA-, QB+, QB-, QC+, signal QC-).
Now, specify the work effect of the SRM drive unit that constitutes like this according to the present invention with reference to Fig. 7 and 8.
As shown in Figure 7, determining the work period according to the control unit in the SRM drive unit of first embodiment of the invention 70 according to institute's sensed current signal of exporting from current detecting unit 50, thereby generation pwm signal, and this pwm signal merged mutually with rotor-position signal from position detection unit 40 input, have the signal of the pwm signal in predetermined work cycle with output, have the signal of the pwm signal of work period of 1 00% with output as lower switch element (QA-) as the top switch element (QA+).
In addition, switch element (QA+, QA-) end after, control unit 70 at the fixed time the section in (T2:100 μ s-200 μ s; By the decision of institutes such as motor shape, material and size) export pwm signal with predetermined work cycle, as switch element (QA+, signal QA-).
Then, (QA+ QA-) carries out switching manipulation according to the signal of exporting from control unit 70 to switch element, thereby electric current (i) is flowed in switched reluctance motor 20.
At this moment, switch element (QA+, (in other words, that is, switch element (QA+, the time point that QA-) ends) produces first radial load at the time point place that finish in QA-) " conducting " zone (T1); And the time point place that finishes of section (T2) at the fixed time, produce second radial load, wherein, because the generation of second radial load is than first radial load hysteresis, 180 degree phase places, therefore, first radial load and second radial load are cancelled out each other reducing final radial load, thereby reduce because the noise that radial load produced.
Although above A is operated the description of carrying out mutually, mutually mutually identical with A by B with the operating process of C phase, therefore,, weakened by the noise of the switched reluctance motor that radial load produced according to the radial load that reduces continuously.
Simultaneously, as shown in Figure 8, in the SRM of second embodiment of the invention drive unit, control unit 70 is merging mutually with spontaneous pwm signal from the rotor-position signal of position detection unit 40 outputs, and the pwm signal that has the work period that progressively reduces with output is as the signal of the top switch element (QA+) and lower switch element (QA-).Then, (QA+ QA-) carries out switching manipulation according to the signal of exporting from control unit 70 to switch element, thereby electric current (i) is flowed in switched reluctance motor 20.
At this moment, because the signal of output is the pwm signal that progressively reduces the work period from control unit 70, therefore, there are not switch element (QA+, the zone of QA-) all ending on T1 and T2 zone.
Therefore, the radial load that produces in switched reluctance motor 20 driving processes is weakened, and makes the noise that is produced by radial load reduce.
In addition, although above describe the operation explained the A phase since B mutually the and operating process of C phase and A operate identically mutually, therefore,, weakened by the noise of the switched reluctance motor that radial load produced according to the radial load that reduces continuously.
From above obviously as can be seen, the advantage of switched reluctance motor of the present invention is that the radial load that produces is weakened when switched reluctance motor is driven, thereby reduces the noise of switched reluctance motor.