DE1513648A1 - Circuit arrangement for controlling a battery-operated DC traction motor - Google Patents

Description

FILE-Na ι

Eaton Yale * Towne Inc., Cleveland, Ohio / USA

"Circuit arrangement for controlling a battery-operated DC traction motor *

The invention relates to a circuit arrangement for controlling a battery-operated direct current traction motor a floor conveyor vehicle with a pulse generator fed from the battery for generation a regular sequence of to be applied to the engine Power pulses, the pulse duration of which changes the Vehicle speed can be regulated from the outside, whereby Current limiting means are provided, which automatically when a predetermined level of the motor current is exceeded cause a reduction in the pulse duration.

An earlier German patent application Y 759 VIIIb / 20 1 relates to a Pestkörper engine control system in which the driver of the vehicle uses time duration or duty cycle from applied to a direct current series socket motor DC pulses by switching one on and off

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6AD ORiQiNAL

Number of power transfer gates connected in parallel can regulate between battery and motor. This system has current equalization means to keep the motor current evenly to distribute to the power transistors, together with an automatic current limiting circuit, around the maximum malatrom applied to the motor in direct proportion to the duration or the duty cycle limit the impulses.

The present invention relates to a similar feature body engine control system having a number of new features to improve the efficiency and performance of the system; It is characterized in that the externally operated speed controller is mechanically coupled to the current limiting control means in order to change the predetermined level of the motor current in inverse proportion to the duration of the power pulses in such a way that the current limit increases for pulses of shorter duration and decreases for pulses of longer duration

Another object of the invention is to provide additional protection for the Pahrzeugausrüstung and the driver venn one or more power transistors should adjourn.

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6AD ORIGINAL

In order to improve the degree of effectiveness of the system, be in the engine control system of the invention essentially all control currents and power currents are directed to the motor, so that an increased proportion of the from the battery extracted energy is used to drive the motor.

I ^{1 For} additional protection of the vehicle and driver, the engine control system has an automatic detector to monitor the waveform of the current applied to the engine and to automatically disconnect the battery from the system if a short circuit in one of the power transistors is detected.

The new "inverse" motor current limit control brings a further improvement in vehicle performance with simultaneous protection of the motor against overload and is coupled with the foot pedal to an automatic Switch off current limitation during pulses with a small duty cycle and a corresponding current limitation protection to be effective for pulses with a larger pulse duty factor. This control can the motor receives a stulled current and normal plugging current while the maximum current flowing under other conditions

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is kept within permissible limits.

Thus, a primary object of the invention is to be straightforward Motor control system for PlurfOrder vehicles with improved To achieve efficiency, performance and safety.

Another goal is to create a system that allows the vehicle batteries to be recharged less frequently requires.

Another object is a system with Pestkörper transistor circuits and automatic protection against transistor short circuits or errors.

Another goal is a system that is broad Range can be operated by the driver, from the blocking current and normal braking currents up to the maximum speed in forward and reverse gear, while on the other hand the maximum motor current is regulated automatically and is automatically protected against errors in the transit circuits.

Another item is a motor control system that can be switched off by the driver to run the battery

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to be applied directly to the engine in both forward and reverse gear.

The invention will now be explained in more detail with the aid of some exemplary embodiments shown in the drawing.

Fig. 1 is a block diagram schematically showing a preferred engine control system according to the invention shows,

Figure 2 is an electrical circuit diagram of the preferred transistor circuits for regulating duty cycle switching the power transistors,

Fig. 3 is an electrical circuit diagram of the preferred transistor circuits for automatic operation Limiting the maximum motor current in inverse proportion to the average motor voltage applied to the motor,

FIG. 4 is an electrical circuit diagram of FIG preferred power transistor switching circuits and the protective circuit to automatically switch off the battery in the event of a short circuit one or more power transistors.

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In Pig. 1 is the electric motor to drive the industrial truck preferably a Gleichetrom traction motor 10 with Heihen field windings 11, which are connected to the motor armature winding 10 by means of a reversing switch 12 are. A battery 13 for driving the motor is connected to the system via control relays 14 and a number transistor line switch 15 connected in parallel and 16 connected with high current carrying capacity. These transistor switches can be repeated at the beginning of each Period of an oscillator 17 of constant frequency are closed to individual power pulses from the Battery 13 through the switches 15, 16 to apply to the motor and at an adjustable time during each period of the Oszialltors 17 are opened, depending on Position of a foot pedal 23 to regulate the duty cycle or the duration of the power pulses applied to the motor.

In order to conduct the relatively large battery currents necessary to drive the vehicle traction motor 10, one is considerable number of power switching transistors 15 and required; a preferred system has sixteen such transistors are connected in parallel and are equipped with Stromausgleiohsmittel to allocate the current equipped on the individual transistors.

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A transistor can fail due to a short circuit; if one or more line transistors 15 »16 short circuit have, the GIeion voltage of the battery 13 would be permanent on the motor 10 via the short-circuited transistor, causing the industrial truck to reach maximum speed accelerated, creating a dangerous condition. According to the invention, this Risk minimized by using a waveform search circuit 18 which responds when a constant amplitude of a direct current signal is applied to the motor, or occurs in the system and quickly actuated the relay control 14 to disconnect the battery 13 from the engine control system in the event of a fault should occur.

In addition to protection for the industrial truck and driver against short circuits and faults in the transistor circuits the system also includes means for automatically limiting the amplitudes of the battery current applied to the motor in inverse proportion to the mean pulse voltage applied to the motor 10. So if the forklift truck runs at low speed or stands still, the blocking current and normal braking currents can through the switching system can be applied to the motor without a current limit being applied, while if the

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Industrial truck travels at medium or high speed, current is automatically and progressively limited to prevent excessive current flow that could burn out or overload the motor. This automatic current limitation control is carried out by a feedback circuit with a resistor 20, which is connected in series with the motor 10 and detects the amplitude of the motor current during each current pulse, a feedback amplifier 21, which amplifies this feedback signal, and a switch-off trigger circuit 22, which always then is actuated when the amplified feedback signal reaches a predetermined level in order to terminate the duty cycle on the motor and thereby reduce the motor current. For the desired "inverse ¹ · control, the gain of the feedback amplifier 21 is set in inverse proportion to the adjustment of the foot pedal 23, whereby the gain of the feedback amplifier 21 is reduced and a current limitation is switched off at low motor speeds and, conversely, the gain increases and progressively a desired current limit is achieved at higher speeds.

In FIG. 1, the oscillator 17 is powered by the battery 13 fed to form a regular sequence of constant W-cuboid

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Generate square pulses. Every oscillator pulse triggers a pulse width modulator 28 in the operating state for a variable period of time, which can be set by an adjustable Potentiometer 29 is controlled, which is set by adjusting the foot pedal 23. At the end of this adjustable The modulator 28 ends its time interval Pulse and is automatically prepared for the arrival of the next trigger pulse from the oscillator 17. If that The foot pedal 23 is only slightly depressed, the time constant of the modulator 28 is determined by the potentiometer set to achieve a minimum time constant |; e and the pulse from modulator 28 is automatically terminated almost immediately after the pulse is generated, while, when the foot pedal 23 is depressed to the extreme position, the time constant of this modulator 28 is increased so much that the modulator pulse just before the next trigger pulse or the next Period of the oscillator 17 is ended.

The duration or the duty cycle is the polarity Modulator pulses in the entire range between almost completely “on” to completely “off” by regulating the foot pedal 23 adjustable.

These variable conductive values generated by the modulator 28

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Continuous pulses are pre-amplified and then by a Amplifier 30 amplified to a level sufficient to switch the power switching transistors 15, 16 to effect. So at the beginning of each period of the oscillator 17, all the transistors 15, 16 are actuated to the battery current through conductors 31 and 32 and through conduct transistors 15, 16 to motor 10; at the end of each modulator pulse, the transistors 15, 16 switched to terminate the power pulse applied to the motor 10.

For automatic regulation of the motor current limitation, the motor current is passed through during each power pulse the series resistor 20 checked; the signal generated via this resistor 20 is fed back to the Amplifier 21 applied. When the amplified signal of the amplifier 21 reaches a sufficient level, actuate there is a shutdown trigger circuit 22 to apply a feedback pulse via conductor 74 to the modulator 28 and thus stopping the modulator's activity before its normal period. As mentioned above, regulate the reinforced Pulses from modulator 28 the action of transistors 15 and 16; so if the modulator 28 a feedback-ending pulse from the shutdown

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Receives trigger circuit 22, the transit gates 15 »16 cleared to end the duty cycle of the battery current applied to the motor.

It is known that a direct current series motor Current in proportion to the applied to the motor, Voltage relates, with a shortening of the duty cycle of the power supplied to the motor also the Motor current reduced within permissible limits.

As mentioned above, the invention brings about an adjustment of this automatic current limiting control in a "reverse" to the speed of the vehicle Relationship. This is done by connecting the foot pedal 23 via lever 23a to a potentiometer 34 for gain control, which is in the feedback amplifier 21. For the minimum position of the foot pedal 23 (low Speed or standstill) the gain of the feedback amplifier 21 is sufficiently reduced, to switch off the automatic current limiting control circuit. On the other hand, if the foot pedal 23 is pushed all the way down (high speed), the gain of the amplifier 21 becomes progressive increased by potentiometer 34 in order to set current limits for each speed to the desired extent.

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respectively. So when the vehicle is stationary or moving slowly, the full amplitude of the Blocking current or braking current can be applied to the motor while driving the vehicle with different Speed an automatic current limiting control takes place in order to avoid an excessive current flow to avoid the engine.

The power pulses applied to the motor 10 from the battery 13 through the transistors 15, 16 usually the same square wave form as the pulses generated by modulator 28 because of the transistor transistors 15, 16 are operated during the duration of each pulse of the modulator 28. For protection against short circuits of the transistors 15, 16 is the waveform of the power pulses applied to the motor 10 with the square waveform generated by the pulse width modulator 28 by means of a waveform detector 18 compared; when a constant DC signal is detected in any signal, the detector generates 18 a switch-off signal via conductor 19 to the relay 14 in order to disconnect the battery 13 from the system.

In the event that the vehicle driver bypasses the engine control system and the engine 10 is the full battery

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wants to supply power, the system has bypass switches (indicated in Pig. 1 by switch 35 ^ to bypass transistors 15, 16 and connect battery leads 31 and 32 directly to the engine.

According to Fig. 2 with the preferred transistor circuit, which consists of the pulse width modulator 28 and the preamplifier and pulse amplifier 30, the Square wave pulses from the oscillator 17 at a preferred frequency of approximately 400 Hz to a diode 40 applied via a resistor-capacitor network, which consists of a resistor 41 and a capacitor 42 exists, which performs both a coupling and wave-shaping function. The diode 40 is reversed polarized so that only the negative parts of the square wave signals flow through and to a resistor

43 can be created. These negative parts are via a coupling circuit with capacitor 47 and Resistor 48 to the base electrode of a transistor

44 created.

The transistor transistor 44 is in feedback with a Transistor 45 connected to having a monostable multivibrator or retriggerable delay flop to generate controllable variable time delay.

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The collector of the Traneistore 44 has a resistor 46 is connected to the negative pole and its emitter to the positive pole of the battery 13. In Similarly, the collector electrode of transistor 45 is connected to the negative battery post via a Resistor 50 connected and the emitter electrode is fed from the positive pole. A source of bias 51 is connected between the base and emitter electrodes of transistor 44 in order to make it normally to bias into the non-conductive state.

The circuit connecting the two transistors 44 and 45 in feedback consists of a timing circuit with Capacitor 52, a variable resistor 53 and a fixed resistor 54 connected between the collector of transistor 44 and the base of transistor 45 is located. A coupling resistor 55 connects the Collector of transistor 45 in feedback to the base of transistor 44.

The mode of operation of this circuit is as follows: The transistor., 44 is biased into the steady state by the voltage source 51 in order to be in the non-conductive or "aue ^M" state and the transistor

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usually to be in charge or * at ^w . When a negative pulse from the oscillator 17 arrives at the base of the transistor 44, the transistor 44 becomes conductive, as a result of which a positive pulse is generated at its collector, which is conducted through the capacitor 52 to the base of the transistor 45. This positive pulse switches the transistor 45 from the conductive to the non-conductive state and generates a negative pulse at its collector and thus backwards via the resistor 55 at the base of the transistor 44 "so that the transistor 44 remains in the conductive state".

When transistor 44 conducts, a current flows from the positive battery terminal through the emitter and collector electrodes of transistor 44 and then through capacitor 52 and resistors 53 and 54 to the negative Battery pole This flow of current charges the capacitor progressively so that its left electrode becomes more and more positive over time, in proportion to the time constants of the capacitor 52 and the resistors 53 and 54. Accordingly, charges after a in relation to the time constant of this resistor-capacitor circuit the remaining period of time the capacitor 52 has a sufficiently positive voltage, to stop conducting transistor 44 what

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again the transistor 45 'j becomes conductive causes the circuit to be returned to its original state. So come back to the grassroots of the transistor 44 incoming negative pulse the conductive, non-conductive state of the transistors and 44 during one related to the time constants of capacitor 52 and resistors 53 and 54 Time and after a period of time the circuit returns to its original state. While During the operation of this circuit, transistor 45 becomes non-conductive and a negative pulse is applied to it Collector electrode generated and via a resistor to the base electrode of a preamplifier transistor directed.

The duration of the generated by this multivibrator To control impulses, the foot pedal 23 is connected to a lever system 23a to adjust the value of the potentiometer 53 to be set in the time constant maintenance. When the foot pedal 23 is depressed, the Resistance 53 in the time constant circuit is increased by the time duration or pulse width generated by the modulator 28 to increase.

The transistor 58, the negative pulse changeable 909822/0778

Duration received from modulator 28 works as a preamplifier to amplify the negative pulse and sets the amplified impulse at the connection point of the resistors 59 and 59a in the collector circuit, this amplified Pulse is generated via a resistor 60 and a capacitor 61, which represent a wave-shaping network, directed to the base electrode of a transistor 62, which operates as a power amplifier, is responsive to the pulse and generates a power boosted pulse through conductor 65 to operate transistors 15 and 16.

The power amplifier stage with transistor 62 has a transistor with opposite conductivity with two resistors 63 and 64 in its collector circuit; its emitter electrode is directly with one negative battery pole connected. The amplified modulator pulse is applied to the base electrode of transistor 62 is applied and is amplified to a value sufficient to operate transistors 15 and 16.

As mentioned above, this amplified pulse is sufficient to keep the transistors 15 »16" on "or to make conductive, which in turn connect the battery 13 to the motor 10, whereby the power pulses from the battery to the motor. The transistor

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Ren 15 »16 remain for the duration of the modulator pulse conductive and are deleted after the end of the modulator pulse in order to reduce the amount applied to the motor End power impulse.

From what has been said it follows that the above sequence of events occurs during each period of the oscillator 17 repeats, producing a series of individual power pulses from battery 13 at the frequency of the oscillator 17 is applied to the motor 10; the individual impulses of this series are variable Duration controlled by the foot pedal 23.

For the supply of the bias voltage sources 51 and 65 and for the generation of the oscillator signal 17, it is preferred a combined DC-DC voltage converter used} a corresponding preferred situation is in the earlier application mentioned at the beginning described. However, other conventional oscillators and DC biasing means can be used can be used for the same purpose.

Fig. 3 shows a preferred transistor circuit for the automatic current limiting control of the motor

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As shown, the one in line with the transit gates gets 15, 16 and the motor 10 switched sensing resistor 20 proportional to the motor working current and the current accordingly it generates a voltage across this resistor 20 proportional to the amplitude of the motor applied current pulses. Resistance can purely for this purpose 20 have a very low resistance value, but must be able to withstand large motor currents; a conventional one Measuring instrument shunt has proven to be useful proven.

The pulse voltage across resistor 20 is applied to a pair of cascade transistor stages comprised of transistors 70 and 71 which puncture an A amplifier to amplify the motor current signal and produce an amplified output signal on conductor 76. This amplified output signal is then fed to an Sdmitt trigger circuit which has transistors 72 and 73 which generate an output pulse on conductor 74 when the amplitude of the amplified motor current signal is large enough to actuate the Schmitt trigger circuit. The Schmitt trigger circuit is shown as a block in both Figure 1 and Pig. 2 and referred to as "shutdown ¹¹ trigger 22; as Pig. 2 shows, the signal from there is returned to

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coupling via conductor 74 to the base of the transistor 44 dee pulse width modulator 28 passed.

With the circuit according to Pig. 3, the motor current pulses occurring at the resistor 20 are applied to the base of the first amplifier stage transistor 70 via a conductor 76 and a coupling capacitor 77. The base of transistor 70 is biased by being connected to the junction of two series-connected resistors 78 and 78, which are between the positive and negative battery terminals. The first stage transistor 70 is automatically biased to a suitable value by means of a resistor capacitor network 81 and 80 in its emitter circuit; its collector is fed via a resistor 87 connected to the negative battery pole,

From the collector circuit of transistor 70, the motor current pulse signal is passed through a coupling capacitor 82 to two variable resistors or potentiometers connected in series. 83 and 34 headed. The resistor 83 is variable in order to provide an initial graduation of the gain of the amplifier stage; the potentiometer 34 is with the foot pedal 23 through the

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mechanical lever mechanism 23a connected to the driver to allow the gain of the amplifier im "inverse" relationship to the adjustment of the foot pedal to control.

The second amplification stage with transistor 71 is essentially identical to the first stage and generates an output signal on conductor 76 to the Schmitt trigger circuit with transistors 72 and 73.

The transistor 72 is normally in a conductive state State biased by connecting its Baals to the junction of two capacitors 91 and 93, the connected in series with a resistor 88 between the positive and negative battery terminals. As a result, the base of transistor 72 receives a suitable voltage to make it normally conductive. The second transistor 73 of the Schmitt trigger 22 is connected with its collector electrode via a resistor 96 to the connection point of the resistors 94 and located in the collector circuit of the transistor 72 tied together. The emitter of transistor 73 is directly connected to the emitter of translator 72 and on the other hand across a resistor 97 connected to the positive battery terminal. A resistor 99 connects the collector of the

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Transistor 72 with the base of transistor 73 in the forward direction and a feedback capacitor 101 connects the collector electrode of the transistor 73 to the collector electrode of the transistor 72.

As mentioned above, transistor 72 is normally conductive and transistor 73 is normally non-conductive since its base is connected through resistor 99 to the more positive voltage of the collector of conductive transistor 72. After the arrival of a pulse with a sufficiently positive amplitude from the second stage amplifier 71, the transistor 72 becomes non-conductive; the more negative voltage on its collector electrode reaches the base of transistor 73, where it is switched to the conductive state. When transistor 73 conducts, capacitor 101 is progressively charged by the current flowing through resistors 94, 95, capacitor 101, transistor 73, and resistor 97. This Ladungepotential has such a direction that the line dta transistor 73 is turned off after a fixed period of time when the voltage across the capacitor reaches a sufficient Wtrt set back whereby the circuit to its original state and the transistor 72 is conductive and transistor 73 is nlohtleitend.

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The voltage at resistor 20, which is proportional to the motor current, is thus amplified by transistor stages 70 and 71 and the amplified signal is applied to the Sohmitt trigger circuit with transistors 72 and 73. The gain of these gain stages 70 and 71 is controlled by the setting of the potentiometer 34, which is connected to the foot pedal 23 for "inverse" adjustment. If, consequently, the foot pedal 23 is depressed in order to apply a larger mean pulse voltage to the motor, the gain of the feedback amplifier 21 is progressively increased, so that a motor current with progressively lower amplitude through the resistor 20 is sufficient to control the Schmitt trigger circuit 22. On the other hand , if the foot pedal 23 is not or only slightly depressed, the gain of the kick coupling amplifier 21 is kept very low, so that the automatic current control system is essentially ineffective.

When the motor current signal has sufficient amplitude has to operate the feedback loop, the Schmitt trigger 22 on conductor 102 produces a positive Pulse generated across the coupling capacitor 100 and the Conductor 74 to pulse width modulator 28 migrates. As

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Fig. 2 shows this becomes positive feedback pulse is applied directly to the base of transistor 44 and renders it non-conductive to reset modulator 28 and terminate its pulse. How nice mentioned, this shortens the duration of the operation of the pulse width modulator and, on the other hand, cancels the Transistors 15, 16, thereby reducing the power pulse applied to the motor by the battery. Accordingly, the described operation of the automatic current limit control circuit results in a reduction the power pulse duration applied to the motor 10 and, consequently, a reduction in that applied to the motor applied mean current. The described feedback before gear is applied to the motor each time Pulse repeated until the sensing resistor 20 decides that the current conducted to the motor 10 is not more than the predetermined value. Then the current feedback signal applied to the Schmitt trigger 22 is no longer of sufficient amplitude to control this trigger 22 and the pulse width modulator 28 operates during its normal period unaffected by the current limiting control.

Fig. 4 shows details of a preferred power circuit for applying the power pulses of

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the battery 13 to the motor 10 and also shows a preferred circuit for switching off the battery 13 in the event of a short circuit or failure of the power transistors.

The amplified pulses of the modulator 28 and amplifier 30 are taken from the connection of the resistors 63 and 64 and applied to the base of a transistor 105 which, as a single stage amplifier, operates all of the power transistors. Typically, transistor 105 is biased by voltage source 106 so that it is non-conductive, but rather after the arrival of a negative pulse from amplifier 30 becomes conductive during the negative pulse, so that current can flow from its collector to the emitter. This stream flows through a resistor 107 to the base of a driver transistor 110, which puts it in the conductive state is switched. Driver transistor 110 is then maintained to supply current to the base of switching transistor 15 flows; so when the driver transistor 110 becomes conductive, it operates the transistor 15. Each amplified upon arrival Impulses from the modulator 28, the further amplifying transistor 105, the driver transistor 110 and the switching transistor 15 become conductive and conduct current from their collector to the emitter.

BATH

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The switching transistor 15 is connected with its collector and emitter electrodes in series between conductors and 115 and is thus connected in series with the motor 10 and the battery terminals 13. Flows according to this circuit Current from the positive battery terminal through the current sense resistor 20 via the conductor 115, through the transistor 15, through a current compensation resistor 111 and from there via the conductor 151 to the motor 10 and then to the negative battery post. So when the transistor 15 is conductive, the Battery power is directed to motor 10 as mentioned above.

A number of other transistors, including transistors 16 and 113, are connected across conductors 115 and 151 in parallel with transistor 15 and all conduct battery power to the motor. Each of these additional transistors also has a driver transistor (not shown) which is similar to the driver transistor 110 of transistor 15 and connected in the same manner. All these driver transistors are fed together by the amplification transistor In the same way as described above, via their corresponding transistors 16 and 113 etc. together to conduct the battery currents to operate the motor.

Uli den von Jfdt "d * r Tran" i "tor" n 15, 16 and 113 BATH ORIGINAL

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To limit the current left and to ensure that the current load is evenly distributed over all transistors, a current limiting resistor Hl ₁ 112 and 114 is connected in series with each of these transistors. In the earlier application cited above, it is shown that a number of transformer windings coupled to one another can be used alternately for current balancing purposes in order to distribute the operating current evenly over the transistors.

The power circuit according to the invention, however, eats more efficiently than that previously proposed, in that all the battery current used for control purposes by the driver transistors such as 110 and the amplifying transistor 105 is applied to the motor IU together with the power pulses transmitted by the switching transistors 15 etc.

When the control current is traced through the motor circuit, it becomes apparent that the collector electrodes of the amplification transistor 105 and the driver transistors 110, HOa and HOb are all connected to the conductor 151 which leads to a terminal of the motor 10. In the reinforcement

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transistor 105, the current is conducted between the collector and emitter electrodes to the base of the driver transformer 110 and the other drivers 110a and 110b and then flows from the emitters of these driver transistors to the base electrodes of the switching transistors 15, 16 and 113 and from their emitters to the conductor 115, which leads to the positive battery pole. In a similar way, the current between the collector and emitter of the driver transistors, for example transistor 110, is also conducted through the base to the emitter of the switching transistors 15, 16 and 113 to the conductor 115. Furthermore , as mentioned above, all the collector-emitter currents of the switching transistors 15, 16 and 113 are conducted in series to the motor 10. It can be seen that the total applied by the amplifier 105, the driver transistors 110, 110a and 110b and the switching transistors 15, 16 and 113, the current flowing to the motor 10 to provide for useful work.

Fig. 4 shows a circuit for automatic disconnection of the battery in the event of a short circuit or fault in one of the power switching transistors 15, 16 and 113. As can be seen, this function is provided by a flip-flop circuit with transistors 138 and 139 and by a waveform -Search transistor 13 ¹ I exercised.

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In the fkip-flop circuit, transistor 139 is normally conductive and transistor 138 non-conductive; a current through the conductive transistor 139 feeds either the Forward relay winding 12b or the reverse relay winding 12a, depending on the position of the reversing switch 1 ^ 7 of the driver, The other switches in series are II8 and 119 normally closed while the vehicle is in operation; the switch II8 is activated by the ignition key operated and the switch 119 closed when the driver is sitting in the industrial truck.

If one follows this series connection in Fig. 4, it can be seen that when all switches are closed, Current from the positive battery post through the normally conductive transistor 139 and through one of the relays 12a or 12b flows to the negative battery pole.

In the upper part of FIG. ¹ I it is shown that the relay windings 12a and 12b operate relay switches 151 and 152 and 154, respectively, which serve to connect the series motor windings 11a and 11b to the motor armature 10 and the negative battery terminal.

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To operate the vehicle in the forward direction, the switch 147 operated by the driver is placed to the right in order to feed the relay 12b, which in turn controls the Contact 154 closes and contact 153 opens. This brings the motor windings 11a and 11b in connection the negative Batteriqpol via the contact 154 and with the Armature of motor 10 via normally closed contact 152. Similarly, when the switch 147 is placed to the left or switched to reverse, the relay winding 12b is switched off and the relay winding 12a energized to close contact 151 and open contact 152, causing motor windings 11a and 11b in opposite polarity direction between motor armature and battery.

According to the invention, a waveform search circuit compares the waveform of the pulse width modulator 28 with the waveform of the power pulses applied to the motor 10 to determine when a constant ODC current from the one or another waveform is generated, indicating a failure, then to turn off relays 12a and 12b and to disconnect the battery 13 from the motor 10.

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This search function is performed by transistor 134. The signal from pulse width modulator 28 is applied to the base of transistor 134 via conductor 156 and resistor 132. In a similar manner, the power pulses applied to the motor and appearing on conductor 151 are also fed to the base of transistor 134 via a resistor 130. The power pulses of the conductor 151 are 180 ° out of phase with those of the pulse width modulator 28, so that during normal operation the base of the transistor 134 always receives a negative voltage from one or the other of these pulse-shaped waves and the transistor 134 accordingly remains conductive. The base of the transistor 134 is biased from a bias voltage source 135 via (. -Inen resistor 133 and is via a resistor l, " ^{..: |} Ern collector

of a transistor 123 connected to receive elae positive span: /.: - ng from the battery. The transistor 134 is therefore normally conductive and applies a positive voltage via a resistor 137 to the base of the flip-flop translator 138 in order to normally make this non-conductive and the transistor 139 conductive.

If the from the pulse generator 28 or from the power switching transistors 15, 16 and 113 tribal negative

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Impulse stop, which indicates a short circuit or failure of the circuit, the positive bias voltage on transistor 13 ¹ J makes it non-conductive. When the transistor 13 ¹ J is non-conductive , a negative voltage is passed from its collector via the resistor 137 to the base of the transistor 138, whereby the state of the flip-flop circuit is reversed and the transistor 138 is conductive and a transistor 139 is non-conductive . As mentioned above , when transistor 139 becomes non-conductive, control relays 12a and 12b are turned off to isolate the battery from the motor. If, therefore, the transistor lj> h detects a short circuit in the switching transistors or failure of the pulse width generator 28, it reverses the state of the PIIp-flop translators 138 and 139 and disconnects the battery ν ons -v-wor «

If the driver wants to switch off the engine control system and apply the full battery voltage to the engine, he can do this by fully depressing the foot pedal 23 to the extreme position. This closes a switch 145 (on the right in FIG. 4) and applies the battery voltage to a relay 35a. The energized relay 35a closes its contact 35 (top left in FIG. 4), as a result of which the positive battery pole is applied directly to the motor armature 10 .

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If the driver switches the engine control by closing the Switch 1 ^ 5, the control relay 12a or 12b are further fed to the contact 151 or 154 im Keep the motor circuit closed as mentioned above. This puncture is performed by turning off the waveform search circle and in that the transistor 139 remains continuously conductive.

To switch off the waveform search circuit, a companion switch 145a is coupled to the switch 1 ^ 5 in order to be closed when the driver depresses the foot pedal 23 to the extreme position. The switch 145a is connected in series with resistors 122 and 120 and with alternately closed, parallel-connected contacts 152a and 152b of the relays 12a and 12b. When switch 145a is closed, it applies the negative battery voltage from the conductor to conductor 160 through these resistors 120 and 122 and closed contacts 152a and 152b. The negative voltage thus applied to the base of the transistor 13 ¹ I is sufficient to make the transistor 134 conductive continuously; this in turn keeps transistor 139 conductive so that relay 12a or 12b remains energized as desired.

Patent claims:

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Claims (1)

• «ι _ Patent claims: 1. The circuit arrangement for the control of a battery operated motor in a truck »With a pulse generator fed from the battery Generating a regular series of iron to the engine Power output pulse to be applied, the pulse duration of which but change the driving speed can be regulated from the outside, whereby Current limiting devices are provided which automatically reduce the pulse duration when the motor current exceeds a given level, characterized in that the externally operated speed controller (23) is mechanically coupled to the current limiting control means (20, 21, 22) in order to achieve the specified level of the motor current in the inverse ratio sur to change the duration of the power pulses in such a way that the current limit for pulses of shorter duration increases and is reduced for pulses of longer duration. 2. Arrangement according to claim 1, characterized by a Oscillator (17) to generate a regular sequence of control pulses, battery-fed power pulses 909822/0778 Generating means, which are actuated in response to the control pulses, to apply line pulses of the same frequency as that of the control pulses to the motor and means sun comparison of the waveform of the oiler and the power pulse generating means and kus switching off the battery of motor control systems In the event of failure of the service »impulse erseuge;: id * n means. 3 · Arrangement according to claims 1 and 2 with a tltic trlschen series motor, known by a modulator, the »ur Ers:» ugunc of Zeltdsuer-moöullerten impulses on the. Control! Impulse responds, I / eist die eum mooring ^ ■,: ^; r F nt. * '"i 1" on ü * n engine during Duration of the modulated «! ¹ .,. . ■ ^: ..se e dl ■ ". * ■■>: ■ ■ ι. *«; ·: "address snpulse, Recelalttel. ^ r. ■ ■■■■■. '■ ^r: «: _; , * lu, - of the modulator and the current limitation-Ii; '■; .. * .i ■ ·:'; - «!, and disconnection means, which in the event of failure " - »r ) ' tn ^r cB'.a ⁴ ttcl to switch off the Ba If · nt η modulator and the .Leietungsiuittel responders ": ή. Arrangement according to the Ar: a,; rüchen Ir to 3, grekerrit «■■:,:. z't-nnt by hand-operated original means "to look around the impulse-generating means and to apply the 909822/07 7 8 Battery mn dmn AbsohaltMltt ·! to determine when the pulses cease in order to then disconnect the battery from the pulse means; and, in response to the hand-operated peeling means, means for turning off the peeling means. 5 "Arrangement according to the test 1 bit 4, marked by battery-fed power supplies" to allow repeated switching off of Battori · and motor old a number of electronic, parallel-connected switching means "wipe the battery and motor, each of which only" passes by "Maxlaal Stromaiaplltude can let through, as well as automatic means sun detection of a short circuit ·· In one _{of the switchgear (} and disconnect the battery from the switchgear. 6. Arrangement according to claim 5, characterized in that the set petals on the wave forum respond to the current applied to the motor, and discover a continuous input (^ component bu. 909822/0779 7. Arrangement according to one of the previous claims with a battery-powered oscillator (17) for induction a regular sequence of impulses of constant wave continuity at constant frequency; a modulator (28) from every oscillator pulse is triggered at the beginning of each pulse. to a controllable time interval pulse Generate EU, characterized by a transistor power switch (15, 16) fed by the modulator the full battery voltage to the motor (10) during the entire tent interval of the Hodulatorimpulee through Rückkopplungsraittel (20, 21, 22), which are based on the Motor applied current respond when it has a certain Amplitude exceeds »by the module pulse before its normal perlode see below, regulating means (23) to regulate the given amplitude su, a »broad control means, to regulate the modulator to change the time interval of the modulator impulses »where the erate and the Ewelte means of regulation for common operation in the are mechanically connected to each other in the opposite relationship, which means that when the tent interval is increased, the Modulatorinpulse the given amplitude is reduced and vice versa; and shutdown means that are common to the Address the translator power switch and the modulator, BATH ORIGINAL 909822/0778 as about the battery from the control system and from the motor see below disconnect, veim the circuit breaker or the modulator fail. 8. Arrangement according to claim 7, characterized by according to Choice of operable, hand-operated bypass devices sum Create dt? Battery to the motor for continuous operation, whereby this »bypass means also abachalten the Abachaltmittel serve. 9 · Arrangement according to claim 8, characterized in that several transistor power holders and power supply equalizers are provided, which are connected to the power transistors are connected, the disconnection means detecting a short circuit in each of the power atranslstoren. lo. Arrangement according to one of the previous claims, characterized by a line circuit with a power control transistor, the collector and emitter of which in Series «wipe battery and motor are connected, a driver transistor, deaaen collector and emitter« wipe Baals and one of the other electrodes of the power switching transistor are connected, a Vevatlrkungs- 6AD ORIGINAL 90 9 822/0778 3? transistor, its collector and emitter between the base electrode of the driver transistor and the electrode of the driver transistor that are not connected to the Base electrode of the power so holding transistor connected 1st, lJagen, with the entire base, emitter and Collector currents of the amplification, driver and switching transistors sum of the motor are conducted, and by means of sum Generation and application of permanent nodular pulses the base electrode of the amplification translator, whereby all translators become conductive and energy together apply to the engine. 11, arrangement according to claim 10, characterized by a plurality of switching and driver translators, and zear a driver transistor for each power transistor, where the collector and emitter electrodes of the switching transistors are connected in parallel and the collector and emitter electrodes of each driver transistor are coupled to a different switching transistor. 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