DE2052695A1 - Device for setting the switch-on and / or switch-off angle of the voltage on each part of the winding of a brushless DC motor - Google Patents

Description

NV Philipe ¹ Gloeilampenfabrieken Eindhoven / Holland

Patent attorney Dipl.-Ing, PritÄ-JoachiM Kupfermann, 2 Hamburg 1 94

"Device for setting the on and / or off switching angle the voltage across each part of the winding of a brushless DC motor ".

The invention relates to a device on a brushless DC machine with a winding consisting of one or more parts and with an electronic commutator consisting of controllable switching elements, via which the operating voltage is applied to the individual winding parts, and a control device that contains at least one position indicator , from which position pulses can be taken that are clearly assigned to certain angular positions of the rotor, for setting the switch-on angle of the controllable switching elements of the commutator.

Such a device has become known from the German patent specification 1 _t 2kk, 2 & 3 . This facility relies on the use of triangular pulses and one

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adjustable threshold voltage to control the electronic commutator. This manner of control is in itself known, e.g., from U.S. Patent 2,809,339 and permitted it is not possible to set or influence the switch-on and switch-off angles independently of one another.

The invention aims to provide another device of the type defined in the opening paragraph, whereby the, in a DC motor with electronic commutation, possible separation of the two in terms of circuitry Functions of the commutator, namely extraction and processing the information about the rotor position and commutation of the coil current can be fully utilized can. It is based on the knowledge that this separation is not only, as in the cited German patent can be made usable for speed control and stabilization, but beyond that, through action on the processing of the information allowed, the characteristic properties of a given engine and to largely influence and / or modify even any motor type.

The device according to the invention is characterized in that at least one delay element controlled by a position pulse with a fixed or variable delay element Time constant for generating pulses with a certain duration and a network for linking them Pulses with specific position pulses and subsequent activation of the controllable switching elements of the commutator is provided with the resulting control pulses.

According to a further training of a facility after

The invention is a further control device with at least one position indicator for generating further position pulses provided the opposite of the first position pulses advance which further control device is connected to the delay elements.

This makes it possible for the delayed pulses to take effect only from a certain, defined speed as this marks the beginning of the delay time by a fixed reference angle compared to the control

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device delivered position impulses is brought forward.

It will be evident that the further control device can be the same as the control device, if the further position pulses are taken from a position indicator, the position indicator for the position pulses seen in the direction of rotation goes ahead.

According to another embodiment of a device according to the invention, at least one device is for short-circuiting of the winding parts concerned during at least a portion of each delay pulse is provided.

This makes it possible for the torque ■

Speed characteristics in the vicinity of idling assume a steeper course and with an approximately constant slope in the Skip the generator area.

According to another development of a device according to the invention is of the outputs of the control device and further control device connected at least a part nixt at least one delay element, the output of which leads to at least one logic circuit in which several these delay pulses can each be linked to a position pulse to form the resulting control pulses.

This makes it possible to change the total current without the phase angle of this current being changed considerably will.

Each delay element is preferably formed by a monostable multivibrator.

Although usually each winding part one

only delay element is assigned, which is necessary in cases in which delay pulses overlap, kar in the reverse case in which the delay pulses do not overlap each other, each delay element be assigned to several different winding parts, whereby the Facility is simplified and cheaper.

According to the invention, two delay elements can be assigned to each winding part, one of which is for Delay of the leading edge and the other is used to delay the trailing edge of the position pulse. Will If the delay lines are chosen to be the same, the length of the control pulses remains constant and only the phase angle changes with the speed. But it is also possible to

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constant different to choose or under influence
of various sizes, for example from the motor current
change.

Each delay element is preferably in this case
formed by a monostabil.e flip-flop.

The invention becomes with reference to the drawing
explained in more detail. Show it:

1 shows the circuit diagram of a direct current motor with electronic commutator according to the older patent application

p. 1830.970.

2 shows a diagram for explaining the mode of operation of this motor.

3 shows the circuit diagram j partially in block

^ form, a first embodiment of the device according to the invention.

Fig. H is a diagram for explaining the operation of this embodiment.

5 shows the circuit diagram of part of a
second embodiment.

FIG. 6 is a diagram for explaining the mode of operation of the exemplary embodiment from FIG.

7 is a diagram which indicates the course of the voltage on the winding as a function of the angle of rotation W.

8 shows the circuit diagram of part of a
third embodiment.

9 is a diagram for explaining the effects ι like the embodiment of Figure 8 '·

10 shows the circuit diagram of part of a
fourth embodiment and a variant thereof; and

11 is a diagram for explaining the mode of operation of the exemplary embodiment and the variant of FIG. 9.

Fig. 12 is a block diagram of one with a
further control device provided 4-phase motor.

13 shows the pulse diagrams belonging to this

Fig. \ K a circuit diagram in which a control pulse is broken down into several partial pulses and

15 shows the associated timing diagrams.

In Fig. 1 iat a brushless DC motor with a control device according to the earlier patent application

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(ΡΗΝ 3 ^ 91) shown schematically to which the facility according to the present invention advantageous. can be turned.

The brushless motor has a winding 1, 2, 3 ι ^ consisting of four parts to generate a rotating field and a permanent magnetic rotor 5 »z.-B. with two poles N and S-. It also contains an electronic commutator. To obtain the necessary information about the current position of the rotor 5, it contains an axially preferred, permanent magnetic sector 6, which extends, for example, over 135 °, and four in the area of this magnet, over the circumference of the stator such as the winding parts 1 to h distributed toroidal cores 7 »which can be saturated by the magnet 5 in the diametrical direction. A winding 8 is attached to each of these toroidal cores, preferably symmetrically with respect to the direction of the field of the magnet 6 , so that there is a change

the size of this field over the entire winding 8 practically no voltage induced.

Each of the windings 8, together with a corresponding capacitor 9 connected in series with it, forms » an impedance circuit 8, 9. All impedance circuits are in parallel switched and verden excited by sawtooth vibrations relatively high frequency, e.g. 270 kHz, generated by an RC-Oazillator with a "unijunction" transistor or Diode with a double base 10. The capacitance of this oscillator is formed by connecting the four capacitors in parallel 9 »and its charging resistance is the emitter resistance 11. One The base of the transistor 10 is connected to the negative terminal (oV) of the supply source, and its other base is connected to connected to a resistor 12, which on the other hand, as well as the emitter resistor at the positive terminal (+ 15V) of this Source lies.

With a saturated toroidal core 7 branch the impedance of each of the windings 8 practically zero. A appears on the winding or windings 8 with an unsaturated toroidal core 7 High frequency voltage. This is through a tranaistor 13 » E.g. the npn type is rectified, and the one by the

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The collector-emitter piece of this transistor flowing, pulsating direct current is smoothed by a capacitor Ik. Its collector is connected to the + 15V terminal via a resistor 1.5 and its emitter is directly connected to the base of a switching transistor 16, its emitter to the oV terminal and its collector via the corresponding stator winding part 1, 2, 3 or k to the + 15V terminal lies.

With this control circuit, the stator winding parts are fed with very sharp, practically rectangular voltage pulses, and consequently a comparatively good degree of efficiency can be achieved. The diagrams in FIG. 2 show these voltage pulses as a function of the angle of rotation (β of the rotor 5 », with the pulses V« and V on the winding parts 3 and k being shown in dashed lines.

With a commutator motor, you can influence the properties of the motor, in particular its drive or braking torque, by turning the brushes. Correspondingly, the cores 7 with their scanning windings 8 could also be displaced. However, it is more interesting to electronically influence the relationship between the sampling pulses and the excitation or load pulses applied to the stator winding parts. It is namely not only possible to delay the excitation pulses more or less with respect to the scanning pulses, but they can also be shortened or lengthened. In addition, the delay, lengthening and / or shortening can be controlled by an electrical variable, for example by a voltage V _n proportional to the speed and / or by a voltage V n proportional to the torque.

With a first exemplary embodiment of the device, shown echematically in FIG. 3, the input pulses are lengthened without delay by additional pulses of controllable width, as shown in FIG. K.

For each of the switching transistors 16 of FIG. 1, the device contains a network 17t 18 for differentiation the electronic commutator for the ont-

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the speaking part of the winding (e.g. 1) delivered pulses. The input terminal 19 of this network is connected to the base of the corresponding switching transistor 16, and its output terminal 20, via a diode 21, to the collector of the first transistor 22 of a monostable multivibrator, which forms a delay element with an adjustable time constant. The flip-flop circuit shown contains a second transistor 23. The emitters of both transistors 22 and 23 »of the npn type are connected to the terminal oV and their collectors are connected to the terminal + 15V via resistor 24 and 25, respectively. The base of transistor 22 is via a resistor 26, bridged by a capacitor 27, coupled to the collector of the transistor 23, and the base of this transistor is coupled to the collector of the transistor 22 via a capacitor 28 and connected to the +15 V terminal via an adjustable resistor 29. Finally, the collector of the transistor 23 is connected to the input terminal 19 via a diode 30. The whole forms an additional unit, e.g. 21. - ^^ ^re i ^nen corresponding widiing part, e.g. winding part 1.

In the absence of a signal at the input terminal 19, the transistor 23 is conductive and blocks the transistor 22, and the diode 30 also remains non-conductive.

The first line of FIG. 4 shows the rectified and smoothed sampling pulses V ₁ , as they are fed to the base of the switching transistor 16 of the winding part 1 in the circuit of FIG. The second line shows the corresponding differentiated impulses V ₀₀ appearing in point 20. The negative pulse V "_ corresponding to the trailing edge of the pulse V ₁ is transmitted through the diode 21 and blocks the transistor 23" via the charged capacitor 28 until it has discharged again via the resistor 29. As soon as this has taken place to such an extent that the base of the transistor 23 becomes positive again, the flip-flop switches back into its idle state. During the blocking time of the transistor 23, the positive voltage + 15 V is applied via the resistor 25 and the diode 30 to the input terminal 19 and there delivers an additional pulse V, shown on the third line of FIG. 4, so that the base of the corresponding switching transistor 16 delivered control pulse V ₁ ^ (last

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t

j line of Fig, h). is lengthened with time t with respect to the original control pulse V ₁ . The time Δ t is equal to the time constant of the multivibrator and is mainly determined by the capacitor 28 and the resistor 29.

In a motor with an electronic commutator

and with several winding parts, in particular with more than three winding parts, you can divide the tension pulses, e.g. V ₁ to Vk ir ^ one or more, e.g. two groups, within each group or groups these pulses, e.g. V and V or V and V . (Fig. Z) do not overlap. It is then possible to have a single delay element, and possibly also the associated differentiation network of several, for example two winding parts 1 and 3

Assign ψ or 2 and h . The facility is thereby simplified and cheaper.

Such a device for the automatic, adjustable shortening of the excitation pulses is shown in Fig. 5. The entire device contains only two units kl and kZ for the winding parts 1 and 3 or 2 and k. Each of the transistors 13 in FIG. 1 is followed by an inverting amplifier stage with a transistor 35 and an associated collector resistor 36 . The input terminal 19 'of the unit hl is connected via isolating diodes 37 and 37' to the collector electrode of the rectifier transistor 13 assigned to the winding part 1 and 3, respectively, and the base of the

^ Switching transistor 16 for the winding part 1 or 3 is on

'The collector of the associated transistor 35 is connected. The flip-flop controls an inverter with a transistor 38 and an associated collector resistor 39 »and the collector of this transistor is via a diode 30 'or 30" with the collector of the amplifier transistor 35 and with the base of the switching transistor 16 for each of the winding parts 1 and 3. Finally, the adjustable resistor 29 of Fig. 3 is replaced by a fixed resistor 29 'in series with the collector-emitter path of a control transistor IfO, of the npn type Resistance k $ , by one relating to

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the terminal + 15V regulated negative voltage V, which e.g. is supplied by a tachometer generator and increases proportionally with the rotational speed of the rotor 5.

Since the control voltage for the differentiation networks 17 »18 is now taken from the collector of the transistor 13 instead of its emitter, negative pulses V _? 'is generated on the leading edge of each of the position _{pulses V 1} and V', as shown in FIG. These sharp negative pulses drive the monostable multivibrator with the transistors 22 and 23, and during the delay time ^{τ l of} this circuit, negative delay pulses V are generated at the collector of the reversing transistor 38 (third line in FIG. 6). During the beginning of each

of the pulses V ₁ or V ~, the collector emitter strut of the associated reversing transistor 35 is short-circuited by that of the transistor 38 in series with the diode 30 'or 30 ", so that the pulse V ₁ or V_ no longer follows the base of the associated S _c stop transistor 16 can be transmitted before the flip-flop with the transistors 22 and 23 has returned to its idle state and has again blocked the reversing transistor 38. The control pulses V ₁ ^ supplied to the base of each switching transistor 16 (last line in FIG. 6) thus result from Deduction of the pulses V. from the sampling pulses V ₁ or \ ^r ".

If you connect the collector of the transistor 38 to the block k $ and the collectors of the transistors k6 and 47 to the collectors of the control transistors of the power communication circuit, the associated winding parts are short-circuited during at least part of the delay pulse, as indicated by the dotted lines in Fig. 7 which indicates the course of the voltage on the winding as a function of the angle of rotation.

This ensures that the speed-torque characteristics are steeper in the vicinity of idling Assume the course and move into the generator area with an approximately constant gradient.

For each value of the resistor 29 ", kO, and thus for each value of the voltage V, the duration At 'is the deduction

impulse V. practically constant and independent of the rotational speed of the rotor 5 · The corresponding incision 'of the excitation pulses V-g is thus proportional to this rotational speed. With increasing speed of rotation ·;

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however, the negative bias voltage V, and thus the

Resistance 29 '+ ^ O increases, and with increasing resistance, <£ t' also increases, so that a quadratic dependence of the lead angle A cP * on the rotational speed dj0 / dt can be achieved.

Fig. 8 shows a unit ^ J_ of a third embodiment. This unit is composed of a unit h 1 according to FIG. 5 "which is, however, assigned to only a single winding part 1, so that the separating diodes 37 and 37 'and an output diode 30" are superfluous, and a unit J3J. According to FIG. 3 " wherein the adjustable resistor 29 is replaced by a fixed resistor in series with the emitter- collector path of a W transistor hO 'of the npn type, which is controlled by a voltage source V via a base resistor ^ 5'.

As in Fig. 5, the unit U 1 is through the

Voltage at the collector of the associated rectifier transistor 13 is controlled. As in FIG. 3, the unit 31 is controlled by the voltage for controlling the base of the associated switching transistor 16. Between this base terminal and the input terminal 19 of the unit 31 connected to the collector of the associated reversing transistor 35, however, an isolating diode 46 is switched on so that the unit 31 is not triggered by the reversal transistor 38 of the unit fc Η ~ \, at the beginning of each sampling pulse V becoming conductive can.

Fig. 9 illustrates the operation of this embodiment. The three upper lines correspond approximately to those in FIG. 6, if only the solid pulses V ₁ , V. ' and V. taken into account. The fourth and fifth lines correspond to the second and third lines of FIG. K and the bottom line shows the excitation pulses V ^ cut off with trigger pulses V of a duration -dt and lengthened with additional pulses V 'of a duration ^ Jt ¹ .

Of course, and as indicated, the delay elements of both units 31 and 1 can have different time constants and these time constants can be changed under the influence of different quantities. For example, the control voltage V _{D can determine} the unit 31 from the torque of the motor, for example from the motor current

be derived. The additional pulses V " with increasing amplitude of the excitation current pulses are lengthened, so that the maximum drive torque of the motor is increased, or they can be shortened so that the current is limited.

In the fourth to Fig. 10 partially illustrated embodiment, the means for each winding portion or for each group of winding portions containing a unit k ~ \ as that of Figures 5 and 7 "and a unit 31 as that of Figures 3 and 7» a transistor kO * _t serving as an adjustable resistor but without a differential network. The input terminal 20 of the unit 31 is directly connected to that 20 'of the unit-4i, the reversing transistor 35 of Figures 5 and 7 is superfluous because the excitation _{pulses V 1} ^ for the base of the associated switching transistor 16 by additional pulses V ", with the deduction of withdrawal pulses V. are formed so that the corresponding base connection is only connected to the collector of the reversing transistor of the unit 41, via the diode 30 ′ and to the second transistor ″, the flip-flop circuit of the unit 31 ″ via the diode 30.

As shown in FIG. 11, both the trigger pulses V. and the additional pulses V ″ begin with the leading edge of the position pulses V ₁ . The additional input pulse V_

I Ct

of the duration ^) t are longer than the trigger pulses V. with the duration «1t ', and the front part of each additional pulse is suppressed by the corresponding trigger pulse, so that only the excitation pulse V ₁ ^, formed by the additional pulse with the deduction of the trigger pulse the base of transistor 16 is fed.

As indicated, the unit 31 can also be controlled by the unit 41. This requires a second differentiation network 17'f 18 connected to the collector of the second transistor of the flip-flop circuit of the unit kl ^! . The terminal 20 of the unit 31 is then no longer connected to the corresponding point of the unit kl , but rather to the starting point 20 “of this second network. The additional pulses then no longer begin with the leading edge of the scanning pulses V ₁ , but instead, as indicated by dashed lines on the fourth line of FIG. 10 and indicated by At “ , with

Cj

the Ilinterflonke of the not yet reversed withdrawal impulses V.

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The Uinkehi'transistor 38, its collector resistor 39 and the isolating diodes 30 and 30 'are then superfluous, since the excitation pulses V ^ are formed by the additional pulses V'. Another advantage is that it is no longer necessary to ensure that the time constant ^ t of the unit 31 always remains greater during operation than that dt ^{1 of} the unit kl.

By means of the described devices and other possible embodiments and / or variants the same can be seen in the torque-speed characteristics of a given motor, which is already fixed in terms of its dimensions, electronically in a largely arbitrary manner change by changing the duration of the excitation or load pulses and their delay in relation to the sampling

P. regulates impulses through electrical variables, for example as a function of the speed and / or the torque of the motor. For example, the torque-speed characteristics with the delay time (^ t ¹ ) as parameters that are obtained for a motor with permanent magnet excitation are very similar to those of a DC shunt motor with speed control or control by field weakening. This in itself is an important result, since the field of a permanent magnet can hardly be influenced. In addition, the regulation takes place by influencing the data and / or the delay of the excitation or load pulses with practically no loss.

^ Figure 12 shows a block diagram of one with

another control device provided Ί-phase motor. The high-frequency generator A supplies its voltage

to the wound toroidal cores in B, what tension this creates

/ and periodically passed and in blocks C position pulses rectified and fed to the gates F. These position pulses are used as further position pulses in the Blocks D differentiated «Their leading edges resolve in. Delay elements E delay pulses with delay times of 4 t. the end. These delay pulses also become gates F addedx-t. In this case, the further position pulses are phaseiwersclioben by 180 ° with respect to the position pulsesii so that the reference angle here is 180 ° j st.

Here sigmU s ν for the deceleration of the toroidal core

', η

Reference point for triggering the delay signal c selected the starting point of signal a. If one were to use the trailing edge of the signal a as a reference point, so an additional inversion stage H would be required, which is shown in the branch drawn in dashed lines is indicated, which · in that case would take the place of the branch drawn above. The reference angle can therefore be arbitrary to get voted. The effect of this measure can be seen in the pulse diagram in Figure 13. If you look at these impulse images are shown as above the angle ^ l t, so the pulses a, e and b are constant in length and phase. In contrast, the length of the pulse c is the speed proportional. Obviously the impulse c only has an influence on the control impulse f if c overlaps with e. At lower speeds, the pulse e is passed through without delay. This gives the opportunity to To let the motor start with an undiminished high torque and only from a certain freely selectable speed to the Stabilize torque-speed behavior. The delay times ^ t can then be selected to be very large.

A circuit diagram is given in Figure 14,

that makes it possible to split a control pulse a supplied by a toroidal core channel into several partial pulses, which by certain angles are shifted from one another and their length depends on the speed. In the example shown are plus the (differentiated output signals from eight toroidal core channels given to direct inputs and additionally four toroidal signals to inverting inputs of an OR gate, so that twelve equidistant pulses per period appear at its output, each with a delay element Trigger E. As usual, four of the toroidal core signals are fed to the AND gates F and there with the signal c of Delay line linked. The result is the control pulse f, which from Fig. 15 »as can be seen from the pulse diagram, consists of four speed-dependent individual pulses.

The main advantage of this control option is that there is a certain change in the total flow angle a relatively smaller change in the phase shift corresponds to there are also advantages, especially at higher speeds,

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'' ■? Π R 9 R 9 R

visibly fluctuates in the torque. L Kf Ό 4, s) * J \)

Although in the described embodiments inductive components are used as position indicators it will be evident that all kinds of position indicators are suitable, such as Hall elements and capacitive position components.

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Claims (1)

1. Setup on a brushless DC machine with a winding consisting of one or more parts and with an electronic commutator, consisting of controllable switching elements via which the operating voltage is applied to the individual winding parts, and a control device which contains at least one position indicator from which position pulses can be taken that are clearly assigned to certain angular positions of the rotor, for setting the switch-on angle the controllable switching elements of the commutator, characterized in that that at least one delay element controlled by a position pulse with a fixed or variable time constant to generate impulses with a certain duration and a network to link these impulses with certain Position pulses and subsequent activation of the controllable switching elements of the commutator with the resulting Control pulses is provided. 2. Device according to claim 1, characterized in ' that a further control device is provided with at least one further position indicator for generating further position pulses which lead the first position pulses, which further control device is connected to the _{n delay elements.} 3. Device according to claim 1 or 2, characterized in that that at least one device for short-circuiting the relevant winding parts during at least one part each delay pulse is provided. H. Device according to claim 1 to 3> characterized in that at least one part of the outputs of the control device and further control device is connected to at least one delay element whose output leads to at least one logic circuit in dex 'several of these delay pulses are linked to resultant control pulses with one position pulse each is. 5 »Eim-ichtung according to claim 1 to k, characterized in that each delay element is formed by a monostable multivibrator. 209819/0208 JlC 6 .. Device according to claim 1 to 5 »characterized in that each winding part has a single delay element assigned. 7. Device according to claim 1 to 6, characterized in that two delay elements are assigned to each winding part, one of which is the delay Leading edge and the other is used to delay the trailing edge of the position pulse. 8. Device according to one or more of the 'preceding claims, characterized in that each Delay element is assigned to several different winding parts. 209819/0208 ft Blank page