DE2017033C3 - Arrangement for regulating the induced armature voltage of a DC motor - Google Patents

Description

3. Arrangement according to claim 1 or 2, wherein Auslegeschrift 16 963/1967 known arrangement for the collector of the comparison transistor with the 5 ° regulation of the induced armature voltage of a Base of the power transistor is connected, since the DC motor has a bridge circuit, the characterized in that the constant voltage resistance value of the bridge branches is chosen so voltage element (14, IS) between the emitter of that the bridge circuit to the nominal armature voltage Comparison transistor (12) and which can be adjusted in one. In such a standard bridge half (1, 2) arranged connection (8) 55 arrangement leaves the bridge circuit at the same time Bridge zero diagonal (Fig. 1). if the balanced state when the anchor

4. Arrangement according to claim 1 or 2, wherein it is noted what the armature voltage and the the collector of the comparison transistor is affected by the load characteristic. From this design base collector route Another transistor font, it is also known to set the connected to the base of the power transistor 60 target armature voltage a variable resistor in the is, characterized in that the constant bridge zero diagonal of the bridge circuit to the switching voltage element (19) between the in the other th to form a bias voltage, so that the bridge half-arranged terminal (7) of the bridge diagonal voltage depending on the Bridge zero diagonal and the first ohmic armature voltage change is reduced. If ever-resistance (13) the bridge zero diagonal is 65 but the variable resistor is a small resistance (F i g. 2). value, the control sensitivity is reduced,

while the current flowing through the variable resistor is increased during operation. this leads to

to the fact that the bridge circuit leaves the balanced state

It is therefore the object of the invention to create an arrangement of the type mentioned, which has a stable control characteristic for any values of the induced armature voltage, d. H. with the constantly excited DC motor also enables any set speed. The set speed should be within be adjustable over a wide range, and the arrangement should have good voltage and load characteristics for any So RPM within a large range.

In an arrangement of the type mentioned at the outset, this object is achieved according to the teaching according to the invention of the characterizing part of claim 1 gelösl.

Those connected to the base of the comparison transistor or between its base and its emitter Switched ohmic resistors enable the operating range of the comparison transistor to be set. These resistances are advantageously completely in the bridge zero diagonal.

The ohmic resistances are fixed in both halves of the bridge. Hence the resistance adjustment the bridge circuit is also guaranteed at the start of operation, so that the voltage difference between the two the connections of the bridge zero diagonak only from the motor armature voltage and not from fluctuations depends on the voltage of the DC power source. This enables a very precise and stable regulation the induced armature voltage and thus also the speed can be achieved.

The invention is explained in more detail below with reference to the drawings. In it shows

1 shows the circuit diagram of an exemplary embodiment of the arrangement according to the invention and

F i g. 2 shows the circuit diagram of another exemplary embodiment of the arrangement according to the invention.

According to FIG. 1 belongs to the arrangement according to the invention, a bridge circuit which is through the Armature 1 of the DC motor to be controlled, excited by a permanent magnet, one in series with the Armature 1 connected fixed ohmic resistance 2 and fixed ohmic resistances 3 and 4 are formed, those in series with each other and parallel to the series connection of the armature 1 and the ohmic resistor 2 are switched. The bridge circuit has two feed connections 5 and 6 and in the bridge zero diagonal two connections? and 8. The resistance values of the fixed ohmic resistors 2, 3 and 4 are chosen so that the bridge circuit has a balanced (resistance balanced) state assumes when the armature 1 stands still. The resistance value of the ohmic resistor 2 should preferably be quite small because the armature current flows through it Collector of a power transistor 9 connected to the pnp type, the emitter of which is connected to a positive terminal 10 is connected to a direct current source, not shown. The feed connection 6 is with a negative terminal 11 of the direct current source connected. A comparison transistor 12 of the npn type is shown in FIG the bridge zero diagonal has its base connected to terminal 7 via an ohmic resistor 13, while its emitter is connected to terminal 8 via two reverse-biased diodes 14 and 15 as a constant voltage element and connected to the supply connection 6 via an ohmic resistor 16 A variable resistor 17 is parallel to the Eroitter-base path of the comparison transistor 12 switched. The collector of the comparison transistor 12 is connected to the base of the power transistor 9. A capacitor 18 is connected between the base of the power transistor 9 and the negative terminal 11th

Since the ohmic resistors 3 and 4 in the bridge circuit form a voltage branch, their resistance values should be considerably greater than that of the current path from the armature 1 and the ohmic resistor 2 exists in order to keep the power losses small.

However, a control current for controlling the comparison transistor 12 flows from the terminal 7 through the ohmic resistor 13, the resistance values of the ohmic resistors 3 and 4 being dimensioned so that the current flowing through these resistors remains essentially unaffected by the control current. Since the armature 1 has a resistance of a few ohms, if the resistance of the ohmic resistor 16 is a few kilo-ohms, any major influence of this resistor 16 on the bridge circuit can be avoided.

It should be remembered that the resistance values of armature 1 and ohmic resistors 2 to 4 are so are dimensioned so that the bridge circuit is balanced in terms of resistance at standstill. When a Voltage occurs at the positive and negative connections 10 and 11 when the armature 1 is held, a current for charging the capacitor 18 flows through the emitter-base path of the power transistor 9, so that this transistor becomes conductive in order to apply a voltage to the supply terminals 5 and 6 of the To lay the bridge circuit. However, since the bridge circuit is balanced in terms of resistance, there is in the bridge zero diagonal no voltage difference between the terminals 7 and 8. If the resistance value of the ohmic resistor 13 is chosen so that the forward voltage drop across the diodes 14 and 15 is greater than the voltage drop across the ohmic resistor 13, there is a forward bias between the emitter and the base of the comparison transistor 12 is applied. When this bias is greater than the threshold voltage of the comparison transistor 12, a base current can flow, which makes the comparison transistor 12 conductive, so that the base current of the power transistor 9 is maintained to let the supplied DC voltage through.

When the armature 1 is released from a restrained state, it begins to rotate. An induced armature voltage (back EMF) is created proportional to the actual speed η of armature 1, so that the voltage division between armature 1 and ohmic resistor 2 is changed. This brings the bridge circuit out of the balanced state and causes a voltage difference in the bridge zero diagonal between the connections 7 and 8.

With the supply connection 6 as a reference point, the voltage distribution can be determined when the armature 1 can be expressed as follows:

(i)

(2)

E ₅ = voltage between the supply connections 5

and 6,

E ₇ = voltage between connection 7 and supply connection 6, ie at resistor 3, E ₈ = voltage between connection 8 and supply

connection 6, ie at armature 1, R _y = resistance value of armature 1, R ₂ = resistance value of resistor 2, A ₃ = resistance value of resistor 3,

R ₄ = resistance value of resistor 4.

If the bridge circuit is balanced in terms of resistance, the following applies. R _t R _A = ^ ₂ K ₃ , so that the voltage difference in the bridge zero diagonal

E ₀ = E ₇ - E ₈ = 0

When the armature 1 begins to rotate and _{generates a back EMF E 0} , proportional to the actual speed n, the voltage E _{8 changes} . This results in:

E ' = Ki £ 5

₁ +

As a result, the voltage difference E ₀ between terminals 7 and 8 is:

(4)

3 °

Since the magnetic flux in the armature 1 excited by permanent magnets is to be regarded as constant, the back EMF E _{0 of} the armature is E ₀ = K n, from which it follows:

and since the voltage E _BE between the base and the emitter of the comparison transistor 12 is also essentially constant, the actual speed of the armature 1 changes with the opposite tendency to that of the base current / _B. The base current I ₀ is amplified by the comparison transistor 12 in order to produce a control current for the power transistor 9, which _{controls the voltage E 5} between the supply connections S and 6. An increased base current I _B leads to an increased voltage E _n until a balanced state is reached.

It should now be assumed that the actual speed of the armature 1, which is the value η for a specific base current Iβ , is increased to ri for some reason. Then the base current I _B ^au f / 'ß drops to satisfy the equation (7). When the base current drops, the collector current of the comparison transistor 12 is also reduced in order to reduce the conductivity of the power transistor 9, so that the voltage E _{& is} reduced in order to make the actual speed of the armature 1 lower again .

If the actual speed but on η n "falls, the base current is / _ß l to _B" is increased to satisfy the equation (7). This increment of the base current increases the conductivity of the power transistor 9, so that the voltage E ₅ increases and the armature 1 is accelerated again.

In this way, the actual speed π of the armature becomes 1 regulated to a stable setpoint.

It will now be explained how a specific target speed n _{s is} set. Since the base current Iβ for controlling the comparison transistor 12 has a very small value, if

Ebb ^,

η =

KR ₉

_{= K} > _E

(5)

_K , _ K ₁ + R ₂ KR ₂

40

If, on the other hand, the voltage difference E _{0 is placed} between the emitter and the base of the comparison transistor 12 in order to control it, the voltage distribution results:

-R,

and the base-emitter voltage E _{BE of} the comparison transistor 12 is equal to the forward voltage drop Ed across each of the diodes 14 and 15, equation (7) becomes:

: K'Ed 1-

E ₀ = 2Ed - E _BE

(6)

rait

IEd- forward voltage drop across diodes 14

and 15,

E. be = Base-emitter voltage of comparison transistor 12, R _a = resistance value of resistor 13, R ₁₁ = resistance value of resistor 17, I _B = base current of comparison transistor 12.

The following equation is obtained from equation (S):

(7)

60

However, since the forward voltage drop 2Ed across the diodes 14 and 15 is substantially constant and in the normal operating range regardless of the current Therefore, a target rotational speed n _s by adjusting the value of R ₁₃ ZR be made ₁₁ in an area of little "as the first In this case the maximum speed / I _1n O ₁ = K 'Ed, but if a higher value _{is required for W 0111x} , it can be achieved by connecting an additional diode in series with diodes 14 and 15. However, the equation (8) requires Dab the forward voltage drop Ed at each of the diodes 14 and 15 is substantially equal to the voltage drop Ebe 3 ° ^ ^ei base-emitter path of the comparison transistor 12 so that when the voltage 2Ed by other * Device is to set the target speed n _s au some value using equilibrium (7). In this case, 2 £ <must be constant relative to any changes in the supply voltage, since it supplies the target voltage the modified from shown in Fig.2

Leading example, the supply terminal 5 of the bridge circuit is connected to the negative terminal II of the direct current source and the supply terminal 6 is connected to the collector of the power transistor 9, uie series connection of an ohmic resistor 18a and a diode 19 serving as a constant voltage element is connected in parallel to the ohmic resistor Λ , the The cathode of the diode 19 is connected to the terminal 7 of the bridge zero diagonal. The resistance values of the resistors are chosen so that the bridge circuit can be balanced in terms of resistance. The anode of the diode 19 is connected to the base of the comparison transistor 12 via an ohmic resistor 13, and the emitter of the comparison transistor 12 is connected to the terminal 8 of the bridge zero diagonal. The variable resistor 17 is again P? ^rallel * ^for _P S "emitter path of the transistor 12 compared geschal- ♦" r ,; "no.ic ω« «/ Eiteren transistor 20 of the npn Dabci R ₃ the resistance of a circuit arrangement, which results from the resistor 18 a, the diode 19 and the ohmic resistor 3. In the bridge circuit, R ₁ R ₄ = RiR /, so that the voltage difference disappears: E ₀ == E ₁ - E ₈ = 0.

When the armature 1 starts up and _{generates a counter-EMKE 1} , the voltage on the armature 1

Ri + Rz

This results in the voltage E ₀ between the connections? and8 of the bridge zero diagonals:

E ₀ = E ₇ - E _B '=

Since the back EMF E _{0 has} the value K-η , the following applies

With

of transistors 12 and 20 are with_ the ---. Terminal 10 of the direct current source via large ohms see series resistors 21 and 22 respectively

Also in this embodiment, the Brickcnscha'ltung is dimensioned such that it -DE- -dsmäßig while holding the anchor rabgeghc hen is such that d ^g y voltage difference between two ,, the Anschlus "=

_K : -

KR ₂

l +

KR ₂

On the other hand, the voltage difference E ₀ between the connections 7 and 8 of the bridge zero diagonal is applied to the base-emitter path of the comparison transistor 12 in order to control it, this voltage being determined as follows:

E ₀ = E _t - E _BE

-R J ^ Z-

the

■ - With the equation (5 ') the following relation is obtained:

can flow because the Voiwämspan- "= K" \ E _d - E _BE -

EMKE proportional to its actual speed, thereby changing the voltage distribution in de, rBnjckensch * -

EMKE proportio

through the stress distribution

- so Since the forward voltage drop E _d at the diode 19 and the voltage Eg ^ at the base-emitter path of the comparison transistor 12 are essentially constant, the actual speed η of the armature changes proportionally to the base current / _ß . The base current Iß is amplified and then reversed in polarity by the transistor 20 , so that the voltage E ₆ , in the same way as in the exemplary embodiment for FIG. is described, controlled.

For Ebe ^ ,

" With the feed connection 6 as a reference point, K ₁₇

the distribution of tension with held office χ ^^ ^ _{QMamig (r)} written as follows

can be specified as follows: ^ _will .

E ₇ = -E ₅ E ₈ = - E ₅

TlJ

r ₁

Therefore the target speed n _{s can be} determined by setting: (20 ^{6o of} the ratio value - ^ -.

1 sheet of drawings

609628/30

Claims (2)

Λ. The invention relates to an arrangement according to the preamble of claim 1. Claims: _{For he} ^ French Patent 14 33 588 • »an arrangement of the preamble of claim 1 L Arrangement for the regulation of the induced 5 mentioned type for Regdung to mduri ^ Anta armature voltage of a direct current motor from a direct current voltage one from a direct current source via a power transistor supplied, a power transistor supplied by a direct current permanent magnet excited by a permanent magnet nut motors with the help of a fixed ohmic wi-help of a bridge circuit known in the equipped in the derstands, with the output side ίο bridge zero diagonal of the comparison transistor in the power transistor connected bridge series with a constant voltage gear arranged circuit in which one half of the bridge is the armature, the a normal element or a Zener diode or winding in series with a series resistor is a diode with a steep direct characteristic
and in the other half of the bridge ohmic Wi- In one by the magazine bunksenau 1969, resistors are in series, and with one of the 15 Issue 4, p. 104 known arrangement for regulation Comparison transistor controlling the power transistor - the induced Aaker voltage one from one disturbance, whose base-emitter path in the bridge direct current source via a power transistor zero diagonal lies, and its emitter with the fed, excited by a permanent magnet equinox Connection of the bridge zero diagonal electricity motor with the help of a bridge circuit, m is bound, which in turn is one of at least one bridge half the armature winding in Diode existing constant voltage element to the series with a series resistor and in their Pre-tensioning the adjacent connection of the other bridge half ohmic resistors in series the bridge zero diagonal are in the forward direction, and control the power transistor with a relative to the base-emitter path of the comparison the comparison transistor in the bridge zero diagonal, transistor having, characterized marked 25 wherein the emitter of the comparison transistor with the net that the bridge circuit is so balanced connected to a terminal of the bridge zero diagonal is that the bridge is at the connections (7, 8), the setting of the operating point takes place with zero diagonal the voltage is zero when the one potentiometer that is between the base of the Engine armature is held; that of the comparison comparison transistor and the bridge half angetransistor (12) the base is closed via a first ohmic 30, which is ohmic in series see resistor (13) with one terminal has resistors. The resistance (7) the bridge zero diagonal and the emitter with moderate alignment of the bridge circuit on the other Basis via a second ohmic resistor is not guaranteed if the resistance value stand (17) is connected and that the comparison of the potentiometer is changed. This leads again transistor (12) and the second ohmic resistor 35 to a deviation of the adjustment point of the stand (17) are designed so that the quotient of the bridge circuit due to fluctuations in the Spander Base-emitter voltage of the comparison transi- tion of the direct current source. stors (12) and the resistance of the second ohm- Furthermore, from the French patent Role's resistance (17) is significantly larger than the 1 530 223 and French patent Base current of the comparison transistor (12) and 40 1 546 761 corresponding arrangements for regulation the base-emitter voltage of the comparison transistor - the induced armature voltage of a direct current gate (12) known equal to the forward voltage drop on motors where a potentiometer is in a each of the diodes (14, IS; 19) of the constant voltage connected to the bridge halves of the bridge circuit link is. is. In these arrangements, too, the resistance 2. Arrangement according to claim 1, characterized in 45 moderate adjustment of the bridge circuit on the anchor, that at least the first or the catch is not guaranteed when the resistance value second ohmic resistance (13, 17) a setting of the potentiometer is changed. widei stand is. Finally used one from the Japanese