DE3215985A1 - CONTROL DEVICE FOR A VARIETY OF DC MOTORS - Google Patents

Description

! NAGHQeRElCHTj

Control device for a large number of DC motors

The invention relates to a control device for a plurality of DC motors, which with a supply s voltage applied according to a demand signal to switch the motors between driving mode and braking mode and a Carry out speed control while driving.

For controlling the speed of vehicle drives using direct current motors operated in series it is known to connect chopper consisting of thyristors in series with the motors. The speed of the motor is controlled with the help of the width of the voltage pulses sent to the motor can be fed via the chopper, the speed being based on the mean value of the applied power adjusts. A commutation circuit with a capacitor is used to apply a bias voltage to apply the conductive thyristor and to trigger a polarity reversal. The drive motor is in operation when that Vehicle is accelerated while driving and when the vehicle is braked or stopped while braking is brought. For the operation and control of such vehicle engines is by the US-PS 3,559,009,

WS320P-2480 3 543 121 and

3,543,121 and 3,535,503 are known to use a chopper.

In the "Westinghouse Engineer" magazine, March 1973, Pages 34 to 41 describe that the average voltage applied to the motor armature is determined by the setting the on-off ratio on the chopper is controlled, so that the average current supplied to the armature determines the torque of the motor for propelling the vehicle. The individual engines of the vehicle are in driving mode mechanically connected to a direct current source in such a way that the current through the chopper is switched on and the motor circuit flows to ground. When the chopper is turned off, it stops in the choke coil and the energy stored in the inductance of the field winding causes a current to flow through the motor circuit via a polarity reversal diode upright. In braking mode, the motors are switched on again by a mechanical switch and act as self-excited generators, resulting in regenerative or dynamic braking of the vehicle results. When the chopper is switched on, the motor current increases, while the chopper is switched off Chopper the current is fed back into the power supply via the polarity reversal diode.

It is already known from US Pat. No. 4,095,153 to use a microprocessor to control the chopper, to limit the regenerative braking current by setting an upper limit value in the chopper mode and a lower limit value is provided when the chopper is switched off.

The invention is based on the object of providing a control device for a large number of in driving mode and in

WS320P-2480 braking operation used

To create braking operation used DC motors, with which the control is further improved and, in particular, passed directly from idle mode to braking mode can be.

This object is achieved by the invention characterized in claim 1. Further refinements of the invention are the subject of further claims.

The invention with its advantages and features will be explained in more detail with the aid of exemplary embodiments referring to the drawing. Show it

1 shows a known motor control for a plurality of drive motors for a vehicle in driving mode;

2 shows a known engine control for a large number of vehicles in braking mode;

Fig. 3 shows a known motor control based on semiconductor, with which a drive motor either in the Driving mode or braking mode can be switched;

4 shows a motor control according to the invention for operation a multiplicity of drive motors, either in driving mode or in braking mode;

4A shows a further motor control for the operation of a large number of drive motors, either in the driving mode or in braking mode;

5 shows a diagram from which the operating current curve for the driving mode and the braking mode

WS320P-2480 for the

for the engine control according to FIG. 4;

6 shows the current curve for the operating current for the Case that the engine control according to FIG. 4 is in idle mode.

In Fig. 1, a known engine control for a plurality of vehicle drive motors for driving operation is shown. The motors are used as DC motors in series operation / the armature winding A1 of the first motor and the armature winding A2 of the second motor are connected in series with the field windings F1 and F2 of the first and second motors. The armature windings A3 and A4 of the third and fourth motors are in series with the field windings F3 and F4 of the third and fourth motors. This results in two groups of motors connected in series, with the groups themselves being connected in parallel. This circuit configuration can be set by closing switches 1, 2, 3, 4 and opening switches 5 and 6. When driving, a chopper C is used to regulate the current supplied to the motor circuit 10. When the chopper C is switched on, a current flows from the DC power supply 12 via the motor circuit TO to ground. When the chopper C is switched off, due to the energy stored in the choke coil and the inductance of the motor, a current flow is maintained via the polarity reversal diode FWD in the motor circuit 10. The operation of the chopper C in this regard is described in the journal "Westinghouse Engineer", March 1973, pages 34 to 41.

The average voltage applied to the motors is determined by setting the ratio of the switch-off time to

WS320P-2480 switch-on time for

Set the switch-on time for the chopper C. This setting takes place with the help of a control device 14, depending on the demand signal P, with which the driving mode is selected and the middle one desired motor current and thus the mean motor torque is maintained. When the full voltage is on Motor is applied, the Serhacker C works with its normal frequency of about 218 Hertz, whereby it works for about 6% one Switching cycle is switched off.

In Fig. 2, a known engine control for a variety of vehicle drive motors is shown, which in Braking operation works. For the braking operation, switching is carried out in this way with mechanical switches B1, B2, B3, B4 and B5 have the effect that the motor circuit 16 according to FIG. 2 results. In this circuit according to FIG causes regenerative or dynamic braking by operating the motors as self-excited generators. The field windings are connected to one another in such a way that a load distribution between the parallel-connected Generators is forced. In dynamic braking mode, the chopper works in the same way as in driving mode, wherein the on and off ratio is set in such a way that the desired current and the higher motor current causes a stronger braking of the vehicle. When the chopper C is switched on, the current increases in the motor circuit 16. On the other hand, if the chopper C is switched off, the current flowing in the chopper must return via the Umpolungsdiode FWD due to the choke MR to the power supply 12 flow. The control device for the logical monitoring of the operation of the chopper C becomes monitored as a function of a demand signal P to select the braking mode, which is sent via line 15 to the

WS320P-2480 line filter capacitor FC

32Ί5985

Line filter capacitor FC and a voltage is applied via line 17, with which the on-off ratio of the chopper is set in such a way that the capacitor voltage does not rise above the mains voltage

In Fig. 3 is a known control device based on semiconductor circuits for setting a single Drive motor shown on the driving mode or the braking mode. The main chopper C in the form of a thyristor is in a known manner as a function of the demand signal P from a device controlling the conductivity Made conductive or non-conductive so that the mean voltage on the armature winding that determines the engine speed A takes effect. Every time the chopper C is switched on, the one on the armature A and on the engine throttle increases MR effective voltage to the voltage value of the voltage supply 12. When the chopper C turned off is, the voltage at armature A and at the motor choke MR drops to zero. The motor anchor speaks to them mean motor voltage and the mean motor current is proportional to the motor torque. The polarity reversal diode FWD allows the motor current to continue flowing due to the inductance of the motor circuit after the chopper C is switched off. A power transistor TP is made conductive when the motor circuit with the associated Armature A is to run in driving mode in order to propel the vehicle which is connected to the engine. One Power diode DP and the motor field winding F is integrated into the circuit for driving, which the power thyristor TP, the return line 22, the voltage supply 12 and the chopper C comprises. A Brake thyristor TB is made conductive when it is desirable to have the motor circuit including the armature

WS320P-2480 in braking mode

· ^: "-" - .. * ..- ■ .. SUBSCRIBED

- 11 -

to operate in braking mode. In such a dynamic braking operation, one or more of the braking resistors R1, R2 or R3 switched into the circuit comprising the braking diode DB. With a commutation Circuit 24 of a known type, the conductivity of the power thyristor TP is terminated when the motor is in braking mode work and the braking current should flow through armature A.

The power thyristor TP is switched on when dependent from the requirement signal P, the motor circuit should work while driving. This causes a current to flow over the Line diode DP, the field winding F, the choke MR, the motor armature A and the thyristor TP from the chopper C. the ground line 22 back to the power supply 12. Using the circuit for the conductivity control the chopper C is controlled so that the average current in the motor circuit including the armature is determined by appropriate modulation. As long as the chopper is non-conductive, current will flow across it the armature A and the Umpolungsdiode 24 due to the stored in the choke MR and the field winding F voltage maintain.

The Br ems thyristor TB is made conductive in response to the demand signal P, if it is desirable that the motor is running in braking mode in order to generate energy by braking the motor. When the chopper C is turned on is, a braking current flows from the motor armature A, which acts as a generator, via one of the not short-circuited braking resistors R1, R2 and R3, which serve to adjust the dynamic braking level, and also via the braking diode DB, the chopper C, the Choke coil MR and the field winding F and over the

WS320P-2480 brake thyristor TB

REPORTEDJ

- 12 -

Brake thyristor TB back to motor armature A. This causes that a current is maintained in the field winding F in braking operation, which maintains the same direction and is determined in the same way by the chopper C as the field current during driving. When the engine works as a generator in braking mode, an output voltage of opposite polarity is generated, based on the power supply 12. As the field current for driving and the braking mode maintains the same direction, this is for the armature acting in generator mode maintain the same reverse voltage polarity. The direction of the current flow through the armature A changes in braking mode, compare with driving mode. In braking mode, a current flows when the chopper C is open Via the power supply 12, the polarity reversal diode FWD, the choke coil MR, the field winding 30, the braking thyristor TB the armature A and those resistors R1, R2 and R3, which are not short-circuited, via the braking diode DB back to the power supply 12, which is thereby supplied with power. The driving control according to FIG. 3 causes an idling operation, as it is not practicable for an engine control according to FIGS. 1 and 2, of none of which have a driving mode and a braking mode for the motor circuit provides. The engine control according to FIGS. 1 and 2 requires a driving mode in which a sufficiently high armature current is built up to enable a braking operation with adequate braking power and a to achieve sufficiently large residual field flux so that the armature current and the field flux are maintained in the motor will. In the motor control according to FIG. 3, if it is desirable, the motor control can be adjusted in the braking mode an idling operation and without prior driving operation, the power thyristor TP and the braking

WS320P-2480 thyristor TB

Thyristor TB can be ignited, the chopper C is used to generate the desired current level through the Field winding and to maintain the two thyristors in the manner described above. When the braking operation is desired, the coramutation circuit ends 24 the current flow through the power thyristor TP, with which the braking operation in the described Way begins. This means that after idling, it is not necessary to switch to driving before braking operation can be started.

4 shows a control device according to the invention. Four motor armatures A1, A2, A3 and A4 with the corresponding field windings F1, F2, F3 and F3 are arranged in a bridge circuit. When driving, the power thyristor TP and the power diode DP are connected in such a way that the armature A1 and A2 is parallel to the armature A3 and A4, the field windings F1 and F2 in series with the two armatures A1 and A2 and the field windings F3 and F4 in series to the assigned anchors A3 and A4. In braking operation, the braking thyristor ^{TB un (} 3 · the braking diode DB is connected via the connections T3 and T4 to the armatures A1 and A2 parallel to the armatures A3 and A4. This results in a series connection of the field windings F3 and F4 with the armatures A1 and A2 On the one hand and on the other hand, a series connection of the field windings F1 and F2 with the armatures A3 and A4. In this way, a balance of the motor currents is ensured both in driving mode and in braking mode exclude individual motors.

WS320P-2480 One on

AFTER ^ EREI

IOHT f

- 14 -

A transducer TD1 based on the Hall effect is shown in switched on the branch, which comprises the field windings F1 and F2, in order to sample the motor current I1. Another, based on the Hall effect transducer TD2 is inserted in the branch with the field windings F3 and F4 to the Motor current 12 to be determined.

The power thyristor TP is in a circuit in which it controls the currents through the field windings and the Armature of the first branch and the second branch switches, which on the one hand from the series connection of the armature A1 and A2 and the field windings F1 and F2 and on the other hand are formed by the armatures A3 and A4 and the field windings F3 and F4. With the help of the brake thyristor TB the currents are switched, which the third branch from the armatures A1 and A2 and the field windings F3 and F4 and the fourth branch from the armatures A3 and A4 and the field windings F1 and F2 are assigned.

The transducer TD2 samples the current through the field windings F3 and F4 from when both the power thyristor TP and the braking thyristor TB simultaneously after an idle operation be made conductive in order to excite the field windings F3 and F4 in preparation for a braking operation, when the power thyristor TP switches over and initiates braking.

In the circuit arrangement according to FIG. 4, a driving mode can be selectively switched, with the thyristor TP and the diode DP are connected in such a way that a current flow through the first branch and the second branch as already mentioned takes place. In order to selectively set braking operation, the thyristor TB and the diode DB become conductive made so that a current flow over the third and the

WS320P-2480 fourth branch

J215985

iC "- '<3. ^ REACH - 15 -

fourth branch / as mentioned above. In addition, a transitional operation can optionally be provided are made, both thyristors TP and TB are made conductive to the series-connected field windings F3 and F4 to excite and the transition from an idling mode to a braking mode and the transition from a braking mode to prepare for a performance company. The thyristor TP is switched off when it is desirable to provide a braking operation after a transitional operation.

An interrupter CB is provided in the circuit, which counteracts a fault condition with a circulating current protects, the chopper C should not switch to power operation for any reason. The breaker CB would then respond to the line current IL rising above a certain safety value.

The control device CA can as a function of the demand signal and additionally depending on the line current IL, the line voltage LV, the motor currents 11 and 12, as detected by the transducers TD1 and TD2, and the load-dependent current requirement IRW must be effective. The control device CA supplies a current request signal on the output side 1+ to chopper C. In addition, there is a control pulse to switch on the power thyristor TP and a control pulse for switching off the commutation circuit TPC for the power thyristor. A control pulse is also provided to switch on the braking thyristor TB.

As can be seen from the illustration according to FIG. 4A, a transducer is used for this embodiment when driving TD3 in the first branch to determine the current in armature A1 and A2 and in the second branch to determine the current

WS320P-2480 in the anchor

ι AFTER

- 16

provided in anchor A3 and A4. Another transducer TD4 is connected to the second branch to control the current in the armature To scan A3 and A4. In the braking mode, the transducer TD3 is connected to the third branch for determining the current im Armature A1 and A2 and provided in the fourth branch to determine the current in armature A3 and A4, whereas the transducer TD4 is connected to the third branch to determine the current in armature A1 and A2. After idling the transducer TD4 is switched in such a way that the current in the field windings F3 and F4 is detected when both the power thyristor TP and the braking thyristor TB are conductive in preparation for the braking operation.

The transducer TD3 samples two currents and delivers two current values in contrast to the transducer TD4, which only has one Current detected. Therefore the transducer TD4 can only be used for half the time compared to the transducer TD3, to be in operation. The two currents supplied by the transducer TD3 are both with respect to the driving operation and of braking operation recorded additively.

The transducers that can be used for this purpose are commercially available under the designation F. W. Bell Model 5020 Disposal.

The output signal of the transducer TD3, which characterizes the sampled current, should be twice that of delivered to the transducer TD4 while driving and braking Be signal. The transducers TD3 and TD4 work bidirectionally, so that the reversal of the armature current at transition from driving mode to braking mode detected will.

WS320P-2480 The transducer

- 17 -

The transducer TD4 is able to sense the field current through the field windings F3 and F4 if both the The power thyristor TP and the braking thyristor TB simultaneously conduct v / ground after idling. The transducer TD3 records the armature currents both in driving mode and in braking mode. In addition, the transducer TD3 detect a change in the direction of the armature current during the transition from driving mode to braking mode.

The transducer TD3 also detects the failure of the power diode DP, since this one in the failed state Would cause a short circuit across the armature A3 and A4 during braking. In this situation it would be necessary that the brake thief is no longer in charge of the To suppress fault current. With regard to the possible time delay, a fuse FS can be provided, which responds to a predetermined fault current to provide additional protection.

In FIGS. 5 and 6, diagrams are shown which show the operational dependency of various voltage forms to illustrate the operation of the invention. 5 shows the current profile in driving mode and in Braking operation for a device according to FIG. 4. If the request signal P applied to the control device CA is a predetermined value, e.g. B. 6 exceeds 0 mA, driving is initiated by igniting the power thyristor TB and begins to conduct at time 30. The curve indicates the armature current of the motor, which, if the Driving thyristor TB becomes conductive, increases. This armature current usually increases by a surge limiter specified curve to assume the desired value, which is determined by the demand signal P.

WS320P-2 480 The associated

The associated field current is described by curve 34. At time 36 when the demand signal has a value below the predetermined level of e.g. B. assumes 60 mA, we initiated the braking operation, with the demand signal P causes the motor current to drop under the influence of a surge limiter. As soon as the field current z. B. after an interval of 2 seconds at time 38 assumes an acceptable value, the braking thyristor TB is triggered and becomes leading. The other current goes to the value zero, as can be seen from curve 32 when the Brake thyristor is conductive. At the same time, the field current is regulated to a suitable value by the chopper C, which corresponds to curve 34 during a predetermined period of time of, for example, 25 milliseconds can take place between time 38 and 40. When the field current is stabilized and when for braking operation like if desired, the power thyristor TB is switched over with the aid of the commutation circuit TBC at time 40, see above that it is not conducting, the armature current is reversed in direction, as can be seen from curve 32. Both the through the curve 34 described field current and the armature current described by the curve 32 can with the help of the Chopper C and under the action of the shock limiter increase to after a predetermined period of time, for example 25 milliseconds to adjust to a value that corresponds to the desired braking effect. The length of time between time 38 and time 40 as well as between time 40 and time 42 can empirically for predetermined vehicles can be determined and can from the value of 25 milliseconds given above, for example differ. At time 4 4 no further braking effect is desired, so that the chopper C can work ceases and the armature current and the field current go back to the value 0, as shown in curves 32

WS32OP-2480 and 34.

and 34 is apparent. If desired, as above described / returned to driving operation.

In FIG. 6, the current curve for idling operation of the device according to FIG. 4 is shown. It becomes of it it is assumed that the vehicle is idling at time 50 after it was previously in driving mode and that the chopper C is non-conductive. In this state, both the field current and the armature current are zero. In order to trigger the braking operation at time 56, both the power thyristor TP and the braking thyristor are activated TB ignited and conductive, so that a field current builds up to a value controlled by the chopper C. will. As soon as the field current has stabilized, the power thyristor TB is switched over at time 58, see above that the armature current, as shown by the curve 52, has an inverse, corresponding to the field current according to the curve 54 Value as determined by the action of the chopper C, which is these current values in the Brake operation controls. If the braking operation is no longer desired due to the demand signal P, listen the chopper C to conduct current so that the armature current and the field current go back to the value zero.

The way in which the chopper is ignited and the switching signals supplied by the control devices CA. to set the power mode or the braking mode or idling mode according to FIGS. 5 and 6, is known per se.

WS320P-2480

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Claims (1)

Claims (_LJ control device for a large number of DC motors, which with a supply voltage accordingly a demand signal can be applied to the motors to switch between driving and braking, characterized, - that the motor circuit comprises a first pair of connections, between many things a first branch with the anchor and the Field winding of the first motor and a second branch with the armature and the field winding of the second motor can be switched is, - that the motor circuit comprises a second pair of connections, between which a third branch with the armature of the first motor and the field winding of the second motor as well as a fourth branch with the field winding of the first motor and the armature of the second Jiotor is switchable, - That the power supply via a first switch is connected to the first pair of terminals and a current flow in a first direction through the Causes armature of the first and second motor, FS / B - And that in braking operation the voltage supply is connected to the second pair of terminals via a second switch and causes current to flow in a second direction through the armatures of the first and second motors. 2. Control device according to claim 1, characterized in that - That a responsive to the demand signal control device is present, which on the one hand with the first Switch is coupled to make this conductive while driving and on the other hand coupled to the second switch is to make it conductive during braking. 3. Control device according to claim 1, characterized g e k e η η ζ e i c h η e t, - That the motor circuit in a first bridge arrangement between the first pair of connections, the first and second Branch in parallel and in a second bridge arrangement between the second pair of connections the third and fourth branch in parallel. , 4. Control device according to claim 1, characterized marked, - That the first switch comprises a first power diode, which a current flow through the armature of the first and allows second motor in a first direction, - And that the second switch comprises a braking diode which one through the armature of the first and second motor Permits current flow in a second direction. 5. Control device according to claim 1, characterized in that - That the control devices make the first and second switches optionally conductive to at least the WS320P-2480 ο Field winding of a motor in preparation for braking operation to excite. 6. Control device according to claim 1, characterized marked, - That between the third and fourth connections, the third branch with the armature of the first motor and the field winding of the second motor and the fourth branch with the field winding of the first motor and the armature of the second Motor is switched, - That with the first branch a first current sensor is connected to a first signal corresponding to the driving current in to supply the first and second branch and according to the braking current in the third and fourth branch, - and that a second current sensor is connected to the second branch to generate a signal corresponding to the traction current in the second branch and in accordance with the braking current in the third branch. 7. Control device according to claim 6, characterized in _f - That the control devices respond to the demand signal and the first and second signals of the current sensors in order to selectively make the first switch conductive for switching on driving mode and the second switch for switching on braking mode. 8. Control device according to claim 6, characterized in that - That the first current sensor is connected between the first and third connection and between the second and fourth connection is. WS320P-2480 9. Control device according to claim 6, characterized marked, - That the first current sensor, the current flow between the first and third connection and between the second and fourth port scans. 10. Control device according to claim 6, characterized marked / - That the first current sensor on the direction of the current flow with respect to each individual armature of the first and second motor responds. 11. Control device according to claim 6, characterized / - That the second current sensor is responsive to the flow of current in one of the field windings of the first and second motors. 12th Control device according to claim 1, characterized marked / - That the first switch and the second switch the field windings energize the first and second motors in the same direction. WS320P-2480