Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
  • H02P9/10—Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load
• • 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
  • H02J7/24—Regulation of the charging current or voltage by variation of field using discharge tubes or semiconductor devices
  • H02J7/243—Regulation of the charging current or voltage by variation of field using discharge tubes or semiconductor devices with on/off action

Definitions

• the present invention relates generally to alternators or alternator-starters of motor vehicles, and more particularly to a device intended to produce a signal representative of the excitation current flowing in the rotor of such a rotating machine.
• the degree of excitation of the alternator is given by the shape of the excitation control signal (typically a signal with pulse width modulation PM) applied to the power semiconductor which determines, in association with a freewheeling diode, the current in the excitation winding.
• the excitation control signal typically a signal with pulse width modulation PM
• PM pulse width modulation
• the object of the present invention is, by means of means capable of being monolithically integrated, in particular with an excitation regulator, to generate in a reliable and stable manner as a function of temperature, a signal representative of the current actually flowing in the excitation winding of an alternator.
• the means for generating the second signal comprises means capable of generating digital information representative of the first signal while the controlled switch is in the on state, and means for selectively memorizing said digital value from the moment when the controlled switch becomes blocked.
• the means for selective storage of the digital value comprises an up / down circuit receiving on an input a blocking signal established from the zero crossing of the current in the controlled switch.
• the means for generating the second signal further comprises a comparator receiving on a first input the first signal and on a second input an analog signal obtained by conversion of said digital information and whose output drives an input of said counter / down counter circuit intended for determine the direction of up / down counting.
• the means for generating the third signal also comprises means for converting the output current into a reverse output current, and a selector capable of selectively activating the output current conversion means.
• the output current conversion means comprises a current mirror circuit.
• this means being sensitive to the on or blocked state of the controlled switch and being able, while the controlled switch is in the on state, to generate the second signal from the first signal and, while the controlled switch is in the blocked state, at generate the second signal by memorizing the first existing signal before blocking of said controlled switch.
• FIG. 1 shows the diagram of a circuit according to the present invention
• FIG. 2 illustrates the shape of an excitation control signal, of an excitation current, of a current passing through a excitation control switch as well as two voltages intervening in the circuit of figure 1.
• FIG. 1 there is shown a circuit which comprises in its left part in the figure, conventionally per se, a winding FD constituting the excitation winding or rotor winding of a vehicle alternator or alternator-starter automotive, a power transistor Tex, preferably in MOS technology, connected in series with the winding FD between the output voltage Ualt of the alternator (corresponding to the battery voltage) and earth.
• a freewheeling diode is mounted in anti-parallel with the FD winding.
• the current which circulates in the transistor Tex is noted Iex, while the current which circulates effectively in the winding FD is noted lexc.
• the gate of the transistor Tex receives an excitation control signal.
• the circuit 10 firstly comprises a transistor Tm mounted as a current mirror with the transistor Tex.
• This transistor TM has its source connected to the voltage Ualt and its gate connected to the gate of Tex.
• the transistor Tm is produced with the same basic cells as the power transistor Tex. In the example chosen here, it suffices to use to make Tm a number of elementary cells equal to the thousandth of the number of elementary cells of the transistor Tex.
• the proportional copying of the current Tex in Tm implies that the three terminals of each transistor are respectively at the same potentials. We have seen above that the sources and the grids of the transistors are connected together. With regard to the drain potentials, it can be seen in FIG. 1 that the drains are connected together via the inverting and non-inverting inputs of an operational amplifier A1, which has the inherent property of maintaining its two inputs at the same potential. The proportional feedback condition is therefore fulfilled.
• the drain of Tm is further connected to the emitter of a bipolar PNP transistor Tl, the base of which is driven by the output of Al.
• the measurement circuit 10 further comprises a resistor RI connected between the collector of Tl and the ground, and a resistor R2 and a Zener diode clipper DZ1 both mounted in series between the Tex drain and the ground.
• the collector of T1 is also connected to the non-inverting input of an operational amplifier A2, which by definition draws no current.
• the current II on the collector of Tl is therefore equal to the current Im, except for the base current of Tl which will be neglected here.
• This current produces at the terminals of RI a voltage Ul equal to Rlxll, and it is understood that this voltage Ul is in the form of a signal of the same waveform and of level proportional to the current Iex in Tex.
• the resistor R2 and the clipping diode DZl (the reverse voltage of which is preferably chosen to be 5 volts) generate on their common terminal a logic signal EN representative of the open or closed state of the transistor Tex.
• Tex if Tex is closed, a current flows in R2 and DZl and the signal EN is at logic level "1"; if, on the contrary, Tex is open, a reverse current flows in SZ1 and R2 and the logic signal EN is located at a low level below zero volts of the ground, level corresponding to the junction voltage of DZl, typically -0, 8 volts, which constitutes a logic level "0".
• the storage circuit 20 firstly comprises a CD up / down counter circuit whose parallel outputs (for example on eight bits) are connected to the parallel inputs of a digital / analog converter DAC.
• the circuit 20 also includes an input for a clock signal CK (or alternatively an internal clock) which clock the up and down counting carried out by the DC circuit.
• the operational amplifier A2 mounted as a comparator, receives on its non-inverting input as we said the voltage Ul, and on its inverting input the voltage U2 e output of the DAC converter.
• the purpose of the comparator A2 is to generate a logic signal Up / Dn of up / down counting direction applied to the corresponding input of the up / down counter CD.
• the operation of this storage circuit 20 is as follows:
• the EN signal is at logic level "0" so that the CD up / down counter is frozen; the voltage U2 therefore remains at a constant value;
• the EN signal is at logic level "1" to activate up / down counting in CD; there are two possibilities:
• the CNA circuit delivers a voltage U2 which by feedback is maintained on a value which is closest to Ul. But as soon as Tex becomes open, the counter / down counter CD is stopped , so that U2 keeps as long as Tex is open the last value acquired before the opening of Tex.
• the shape of the evolution of the voltage U2 (in solid lines) is illustrated in FIG. 2. It can therefore be observed that by setting the peak value of Ul (illustrated in dashed lines), the voltage U2 is substantially proportional at the current lexc actually flowing in the winding FD. It will be observed here that the voltage U2 can be directly used as an output of the circuit of the invention. However, in the case of an environment exposed to electromagnetic disturbances, such a signal can be distorted by such disturbances, or by an unexpected shift in ground potential, which can occur in vehicles. In addition, the ohmic value of the resistance RI can vary quite strongly, in particular if it is carried out in monolithic technology.
• Circuit 30 also includes a Corn selector and a current mirror circuit built around MOS transistors T3 and T4, a PNP bipolar transistor T5, resistors R4 and R5 and a bipolar diode D1. More specifically, the movable contact of the selector Com is connected to the collector of T2, while one of its fixed contacts is connected to the cathode of Dl as well as to the base of T5. The anode of Dl is connected to the gate and to the drain of T3, the source of which is connected to the voltage Ualt via the resistor R4. On the other side of the current mirror, the transistor T5 has its source connected to the voltage Ualt via the resistor R5, its gate connected to the gate of T4 and its drain connected to the emitter of T5.
• the other fixed contact of the selector Com is connected to the collector of T5 as well as to an output terminal Sim of the device.
• the operation of the output circuit 30 is as follows. Firstly, the current generator circuit A3, T2, R3 generates at the collector of T2 a current Isl which is proportional to the voltage U2. Furthermore, if an ohmic value equal to that of RI is chosen for R3, then the current Isl is substantially equal to the current Im during the phases where Tex is closed.
• the current mirror T3, T4, T5, Dl, R4, R5 is active to produce at the level of the collector of T5, and therefore on the output terminal Sim , an outgoing current Is2 which is proportional to or equal to Isl.
• junction voltage of the diode Dl situated on the side of T3 makes it possible to ensure identical polarization at the level of T3 and T4, since T4 has on its side to undergo the emitter / base junction voltage T5.
• resistors R4 and R5 are balancing resistors making it possible to maintain good proportionality or equality between the currents Isl and Is2.
• the Com selector allows, by offering an “outgoing current” output mode and an output mode
• Incoming current means greater flexibility in interfacing the device of the invention with an existing motor control device.
• the above device has, as will be seen, good properties in terms of thermal compensation.
• the current Isl or Is2 generated at the output has excellent proportionality (or equality) with the current II itself proportional to the current in the transistor Tex.
• the device described above is advantageously produced in the form of a monolithic circuit, and preferably on the same semiconductor chip as the excitation regulator circuit (comprising in particular the Tex transistor and the diode DL) of the alternator or alternator-starter.
• the transistors advantageously performing the role of current mirrors (namely Tex and Tm on the one hand, and T3 and T4 on the other hand) from the same elementary cells.
• resistors Ri and R3 are advantageously produced on the one hand, and R4 and R5 on the other hand, so that they are exposed to the same thermal conditions.
• the circuit of FIG. 1 is capable of transmitting a signal representative of the excitation current to the motor control device in the form of a current.
• the motor control device has an analog / digital conversion device capable of deriving from this current a digital value usable in the processing that it performs.
• the circuit of FIG. 1 can incorporate, downstream of the terminal Sim, such an analog / digital conversion circuit, the information being in this case transmitted to the engine control device in digital form, for example according to formats or standard digital protocols such as "synchronous bit” or "LIN".

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

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• 2001
  • 2001-03-02 FR FR0103270A patent/FR2821699B1/fr not_active Expired - Fee Related
• 2002
  • 2002-03-01 MX MXPA02010780A patent/MXPA02010780A/es active IP Right Grant
  • 2002-03-01 JP JP2002570371A patent/JP4037270B2/ja not_active Expired - Fee Related
  • 2002-03-01 KR KR1020027014668A patent/KR100809230B1/ko active IP Right Grant
  • 2002-03-01 EP EP02706914A patent/EP1364438A1/de not_active Withdrawn
  • 2002-03-01 WO PCT/FR2002/000751 patent/WO2002071570A1/fr active Application Filing
  • 2002-03-01 US US10/275,007 patent/US6798176B2/en not_active Expired - Lifetime

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