Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
  • H02H7/067—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors on occurrence of a load dump
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
  • H02J7/16—Regulation of the charging current or voltage by variation of field

Definitions

• the invention is based on a generator system according to the type of the main claim.
• Z-diodes are suitable for protecting the vehicle electrical system against overvoltages, such as those that arise especially when operating without a battery. Since these Zener diodes have to absorb high impulse energies, powerful, large and expensive types are required. It is therefore already proposed by DE-OS 27 08 981 (R. 3780 of the applicant) to relieve such Z-diodes in that the output of the generator is short-circuited by means of an auxiliary circuit before the Z-diode is thermally destroyed . However, this measure requires additional effort.
• the system according to the invention with the characterizing features of the main claim has the advantage that the impact energy that the transfer device must absorb to protect the vehicle electrical system against overvoltages during battery-free operation is drastically reduced becomes. Another advantage is that on the one hand standard components can be used, on the other hand this system can be largely or completely integrated. Finally, it is advantageous that the system according to the invention is very susceptible to faults.
• the voltage can be queried in the voltage regulator itself. If the control current of the current flowing through the pick-up device or the output voltage present at the output terminals of the generator is used, a delay-free switchover from the freewheeling diode to the pick-up device is possible. It is particularly advantageous that the time constant of the excitation circuit is reduced and, as a result, the generator can adapt more quickly to the new load conditions. Further advantageous measures for lowering the impact energy which is to be taken over by the protective device result from the description of the exemplary embodiment.
• Figure 1 shows the usual circuit of a generator system with a free-wheeling diode and overvoltage protection
• Figure 2 shows schematically the inventive transfer device with a free-wheeling diode, a Z-diode and a control unit
• Figure 3 the complete circuit diagram of an embodiment is shown. Description of the embodiment
• a generator 1 contains, in a known manner, a phase winding and a rectifier connected downstream of the phase winding, as well as an excitation winding 2.
• the freewheeling diode 13 is a rectifier diode, it serves as a takeover device 4 for taking over the current which continues to flow through the excitation winding 2 after the transistor 30 has been switched off.
• the free-wheeling diode is electrically connected to its terminal 5 (D +) and its anode to terminal 6 (DF).
• the excitation winding 2 is switched on and off via the transistor 30 serving as a circuit breaker.
• a Zener diode 9 is connected to the positive output terminal 7 (B +) and the negative output terminal 8 (cash register) of the generator 1.
• a low-resistance resistor 52, terminal 51, can be connected between terminal 8 and Z-diode 9, at which a voltage drop occurs as soon as a current flows through the Z-diode 9.
• This Z diode serves as overvoltage protection for the vehicle electrical system in the event that a load 11 is switched off, for example, with a switch 10.
• the overvoltage protection with the Z diode 9 thus serves as a receiving device for the impact energy which the generator 1 emits when the load is suddenly reduced.
• the rectifier connected downstream of the phase winding can contain rectifier diodes with an avelanche character.
• the cathode of the Zener diode 9 can also be connected to terminal 5 (D +) instead of terminal 7 (B +).
• the generator 1 If the load 11 is just large enough to take up the characteristic power of the generator 1, then the generator 1 is fully excited when the switch 10 is closed. Now the Open switch 10, the excitation current in the excitation winding 2 must be controlled from its maximum value to its idle voltage value. During this entire transition phase, the generator 1 outputs a higher power than is necessary. The increased power output causes an energy surge, which must be absorbed by the receiving device 9. The energy surge is greater, the longer the transition phase lasts until the excitation current has dropped to the new smaller value. If the field winding 2 is clamped with a free-wheeling diode 13 in the takeover device 4, the transition phase has the longest possible value.
• the take-over device k contains, in addition to the free-wheeling diode 13, a device 14 with breakdown characteristics, such as a Z-diode.
• the diode 13 and the device 14 are, for example, with a connection to the terminal 6 (DF).
• the takeover device 4 contains a changeover device 12 with a switching bridge 112.
• a contact 16 of the changeover device 12 is connected to the free connection of the freewheeling diode 13 and a contact 17 is connected to the free connection of the device 14.
• the switching bridge 112 is located on one side on the terminal 5 (D +) and either switches the terminal 5 through to the contact 16 or the contact 17.
• the changeover device 12 is controlled by a control unit 15 with two input terminals 8, 50, of which the terminal 8 is connected to ground and the terminal 50 is connected to the terminal 5 (D +) or to the terminal 7 (B +). However, the terminal 50 can also be connected to the terminal 51 of the resistor 52 in series with the receiving device 9.
• the freewheeling diode 13 of FIG. 1 is replaced by the rectifier diode 13 and the device 1 4 in the diagram according to FIG. In normal operation, the switching bridge 112 of the switching device 12 is on the contact 16, that is to say the freewheeling diode 13. The freewheeling diode 13 clamps the excitation winding 2 to its forward voltage.
• the switching bridge 112 is switched to the contact 17 by the control unit 15, so that the excitation winding 2 is clamped to the device 14, the breakdown voltage of which is selected to be much higher than the forward voltage of the diode 13, for example 50 volts.
• the rate of change of the excitation current through the excitation winding 2 is also very much larger and thus the time for the reduction of the excitation current is very much smaller. Accordingly, the impact energy to be absorbed by the receiving device 9 also becomes very much smaller.
• the control unit 15 receives the instruction for switching from a suitable size of the generator system.
• the information “current flows through the receiving device 9” can be selected as a suitable size. However, the information can also be used for the control "the voltage of the generator 1 at its output terminals 7 and 8 or 5 and 8 is greater than the predetermined maximum operating voltage, but still less than the smallest possible breakdown voltage of the receiving devices 9".
• the switching device 12, the free-wheeling diode 13 and the device 14 are expediently formed by semiconductor switches, for example by transistors, which allow both switching states, that is to say a similarly low saturation voltage as a free-wheeling diode 13 and an operation of higher voltage According to a Zener diode 14.
• the higher voltage can be predicted relatively exactly from a lower reference voltage of the voltage regulator 3 by means of a control loop in the control unit 15.
• the transition from the low (voltage) of the freewheeling diode 13 to the high (voltage) of the Zener diode 14 can advantageously be delayed such that the circuit breaker 30 of the voltage regulator 3 only to its collector base breakdown voltage and not to its collector voltage. Emitter breakdown voltage is claimed.
• FIG. 3 One exemplary embodiment is shown in FIG. 3 from the large number of possible circuits.
• a comparator 18 is provided, the non-inverting input 19 of which is connected to a reference voltage 35, and the inverting input 20 of which is connected to the switching voltage divider consisting of the resistors 21 and 22.
• the division ratio of the switching voltage divider 21, 22 is selected so that the potential difference between the input 20 and the ground terminal 8 is as large as the reference voltage 35 when the voltage of the generator 1 at the output terminals 7 and 8 - or at terminals 5 and 8 - e ⁇ .va lies in the middle between the predetermined maximum nominal voltage of the vehicle electrical system and the smallest possible breakdown voltage of the Z-diode in the takeover device 9.
• the reference voltage 35 is generated in the voltage regulator 3 in a known manner.
• the output 23 of the comparator 18 is connected on the one hand via a resistor 24 to the base of the transistor 26, and on the other hand via the capacitor 25 to its input terminal 20.
• the collector of the control transistor 26 is above a limiting resistor stood 32 at the base of a calf ladder switch 33, the emitter of which is connected to terminal 6 of the generator and the collector of which is connected via a diode 34 to terminal 5 (D +) or 7 (B +) of the generator; the base of 33 is also connected to its collector via a Zener diode 133 in the manner indicated.
• the semiconductor switch 33, the diode 34 and the Zener diode 133 form the takeover device 4 for clamping the excitation winding 2 of the generator.
• the transistor 30 serving as a circuit breaker switches off and on regularly in order to bring about the required average current through the excitation winding 2. If transistor 30 is switched on, the potential difference between terminals 6 (DF) and 8 (ground) is equal to its saturation voltage, that is to say approximately 0.5 to 1.5 volts. If the transistor 30 is switched off, the induction-related current will initially continue to flow through the excitation winding 2 at the same level; this requires that the potential of 6 rise above the potential of terminal 5 or terminal 7; how far it increases depends on the takeover device 4. If the generator 1 operates in the normal operating voltage range, then the reference voltage 35 present at the terminal 19 of the comparator 18, that is to say the potential 19/8, is greater than the potential difference present between the input terminal 20 and the ground 8.
• the potential of the output terminal 23 of the comparator 18 is therefore only below the potential of the terminal 5 or 7; Current flows through resistor 24 to the base of transistor 26, transistor 26 is conductive, transistor 33 receives a base current predetermined by resistor 32 and also switches through. The field current now flows from terminal 6 through the Transistor 33 and diode 34 to terminal 5; The excitation winding 2 is thus bracketed at a voltage level which is given by the saturation voltage of the switching transistor 33 and the forward voltage of the diode 34, that is to say to a value which is only slightly greater than that of a normal freewheeling diode 13.
• the load resistor 11 is now by means of the Switch 10 separated from the generator (see Figure 1), its output voltage rises to the level of the breakdown voltage of the Zener diode 9.
• the potential at the input terminal 20 of the comparator 18 is now higher than the reference voltage at the terminal 19.
• the output 23 of the comparator is thus almost at the ground potential 8; transistor 26 is de-energized, and switching transistor 33 also initially.
• the potential of terminal 6 thus continues to rise, namely until the breakdown voltage of Zener diode 133 is reached; now the switching transistor 33 draws base current and thus also collector current; the excitation winding 2 is now clamped in a zero approximation to a potential which corresponds to that of the breakdown voltage of the Zener diode 133, ie approximately 50 volts.
• the input terminal 20 of the comparator 18 is connected to its output terminal 23 via the capacitor 25.
• the transfer device 4 can also be switched over.
• the voltage drop generated by the current flowing through the Zener diode 9 and the resistor 52 (see FIG. 1).
• the input terminal 20 of the comparator 18 is to be connected to the terminal 51; the reference voltage present at the input terminal 19 of the comparator 18 is then expediently very small. choose.
• One or more of the bipolar transistors used can also be replaced by MOS transistors.
• the arrangement can also be integrated in a hybrid or monolithic manner.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Eletrric Generators (AREA)

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Citations (6)

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• 1981
  • 1981-04-24 DE DE19813116315 patent/DE3116315A1/de active Granted
• 1982
  • 1982-03-03 WO PCT/DE1982/000042 patent/WO1982003731A1/en not_active Application Discontinuation

Patent Citations (6)

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