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
  • H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
  • H02P9/26—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices
  • H02P9/30—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices
  • H02P9/305—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices controlling voltage
• • 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
  • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
  • H02P23/0077—Characterised by the use of a particular software algorithm

Definitions

• the present invention relates to a method and a device for controlling a polyphase rotating electrical machine, in particular of the alternator or alternator-starter type, comprising a wound excitation and operating as a generator.
• the invention also relates to a rotating electrical machine using this method and this device.
• alternator-starters made very efficient by the implementation of electronic power systems controlled by circuits using digital techniques, based in particular on the use of microprocessors or microcontrollers.
• the microcontroller used includes both a central processing unit, and programmable delay circuits for synthesizing the waveform, called PWM (Pulse Duration Modulation). switching signals.
• PWM Pulse Duration Modulation
• Another example of application of digital techniques is given in document US20040108840, which describes the voltage regulation of an alternator, or generator, by means of a microcontroller controlling the duty cycle of the periodic excitation current of the machine. from sampled values of the DC voltage produced.
• the regulation principle introduces a phase delay in the servocontrol related to the cycle time and the delay of calculation.
• T be the cycle time and Tc be the calculation delay defined by the time that separates the quantity to be enslaved (in particular the battery voltage, but also the excitation current, for example).
• the phase delay ⁇ (f) in degrees at a frequency f is approximated by the expression:
• the cycle time T of the control is equal to the excitation period Te.
• the control loop refreshes once a cycle of excitation the value of the duty cycle.
• This delay in the control loop is therefore strongly related to the switching period of the power transistor, because in general the calculation delay can be defined at the time of design to remain as small as possible, and small before Te / 2.
• the consequence is a practical limitation of the regulation bandwidth to about Fe / 8 to Fe / 10, where Fe is the frequency of the 1 / Te excitation.
• the excitation frequency is chosen in particular according to the power dissipated by the transistor during the switching phases. This dissipated power leads to an increase in temperature of the chip, which is itself limited by the maximum junction temperature allowed by the technology used. This frequency can not be increased without generating new temperature constraints on the switching component.
• the present invention therefore aims to improve the regulation bandwidth without changing the switching frequency of the excitation current. It relates specifically to a method for regulating a polyphase rotating electrical machine operating as a generator, comprising a wound excitation, of the type of those consisting of slaving to a predetermined reference value a DC voltage produced by rectifying an AC voltage. generated by this machine by controlling a duty cycle of a periodic excitation current by means of a microcontroller, or the like, as a function of sampled values of this DC voltage.
• the determination of the duty cycle ratio of the excitation current is carried out by the microcontroller twice during a cycle of the excitation current.
• the determination of the value of the duty cycle is made substantially at the beginning of the cycle, and substantially in the middle of the cycle.
• the value of the duty cycle is determined just before the start of the cycle, and just before the middle of the cycle.
• This determination preferably comprises the calculation of a first and a second switching delay as a function respectively of first and second values of the DC voltage respectively sampled substantially at the beginning and in the middle of the cycle.
• the establishment of the excitation current then results from the equality between the first switching delay and a first result of the decreasing counting of clock signals during a first half of the cycle, and the breaking of the excitation current. results from the equality between the second switching delay and a second result of increasing counting of the clock signals during a second half of the cycle.
• the establishment of the excitation current results from the equality between the first switching delay and a first result of the increasing counting of clock signals during a first half of the cycle
• the breaking of the excitation current results from the equality between the second switching delay and a second result of increasing counting of the clock signals during a second half of the cycle.
• the invention also relates to a device for regulating a polyphase rotating electrical machine, operating as a generator and producing a DC voltage, suitable for implementing the method described above, of the type comprising:
• an analog-digital converter for acquiring a sample of the DC voltage produced
• At least one transistor controlled by the amplified pulses controlling an excitation current of the machine at least one transistor controlled by the amplified pulses controlling an excitation current of the machine.
• the duration-modulated pulse generator comprises, in a remarkable manner, a binary up-down counter, and a comparator between a counting register of this binary up-down counter, able to contain a value of counting, and a memory register of the microcontroller, adapted to contain a value representative of a cyclic ratio of the pulse modulated in duration.
• the regulating device advantageously comprises:
• a second clock generating second clock pulses having a second period equal to the first period divided by twice a first number, preferably 16;
• the duration modulated pulse generator alternately remarkably comprises a binary counter, and a comparator between a register counter of this binary counter, able to contain a count value, and a memory register of the microcontroller, able to contain a value representative of a duty cycle of the pulse modulated in duration.
• the regulating device advantageously comprises:
• first clock generating first clock pulses having a first period equal to a excitation period of the excitation current
• second clock generating second clock pulses having a second period equal to the first period divided by twice a first number, preferably 16;
• a trigger circuit by interrupting the acquisition of a sample of the DC voltage after each sequence of second clock pulses in a number equal to the first number
• a third clock generating third clock pulses having a third period equal to the first period divided by twice a second number, preferably 1024, and connected to the binary counter counting the third clock pulses from 0 to to the second number.
• the device for regulating a polyphase rotating electrical machine operating as a generator according to the invention differs from the state of the art in that it further comprises at least one memory containing at least one program implementing the regulation method described above.
• the invention also relates to a polyphase rotating electrical machine operating as a generator comprising a regulating device having the characteristics specified above. It goes without saying that the invention also relates to the instruction sequences executable by the microcontroller, or the like, of the device according to the invention embodying the control method described, as well as the memory containing these executable instruction sequences.
• Figures 1a and 1b, 2a and 2b show chronograms of clock signals implemented by the method and in the control device according to the invention.
• Figures 1c and 2c illustrate the triggering of acquisition interruptions in relation to the clock signals of Figures 1b and 2b.
• Figure 1d shows the evolution of the counting of a down-counter implemented in a preferred embodiment of the invention, and illustrates the control method according to the invention.
• Figure 2d shows the evolution of the counting of a counter implemented in another preferred embodiment of the invention, and illustrates the control method according to the invention.
• Figures 1e and 2e show timing diagrams of the pulse modulated in duration resulting from the implementation of the method according to the invention.
• Figure 3 is a block diagram of a control device according to the invention.
• the method according to the invention therefore essentially consists in increasing the apparent frequency of the regulation loop without modifying the switching frequency of the excitation transistor so as not to increase the switching losses in the transistor, and therefore the junction temperature of the component. .
• FIG. 1a represents first clock pulses CLK1 driving the cycles of the regulation loop, and whose first period T is equal to the excitation period Te of the modulated pulses in control cycle duration EXC represented on FIG. Figure 1e.
• the first period T of the first clock pulses CLK1 is not decreased, and therefore the excitation period Te either, but the duty cycle during a switching period Te of the transistor is refreshed twice.
• the regulation will decide on the basis of a first measurement of the magnitude to be enslaved by the on-off time of the power transistor, and in the second half of cycle 2, and on the basis of a second measurement of the magnitude to be enslaved, this same regulation loop will decide on the moment when the transistor is turned off.
• phase delay ⁇ (f) being reduced in this way, compared with the phase delay ⁇ (f) penalizing the control devices known from the state of the art as described above, it is possible, while respecting the same phase margin and gain rules, significantly increase the regulation bandwidth.
• This gain reaches a factor 2 if the calculation delay Tc is small in front of T.
• the benefit is an increased speed of servocontrol and better control performance.
• Figures 1b, 1c and 1d illustrate in detail how to refresh twice the duty cycle cycle cycle of the excitation current according to a first preferred embodiment of the invention.
• Figure 1b shows second clock pulses CLK2, having a second period TCKL2 32 times smaller than the first period T. These second clock pulses therefore define 32 time windows, numbered from 0 to 31, in the course of time. a cycle.
• an IRQ interrupt of the microcontroller by means of which the regulation loop is implemented is generated in each time window.
• Time windows numbered 0 and 15, ie those preceding each half-cycle 1, 2, are respectively reserved for the acquisition of a first and second sample of the DC voltage to be regulated, and calculating, based on each of these samples and a set value, a quantity representative of the duty cycle of the excitation current.
• the microcontroller calculates a first switching delay DC1n between the beginning 3 of the cycle and a first switching moment 4 of the transistor in the on state. corresponding to the establishment of the excitation current.
• the microcontroller calculates a second switching delay DC2n between the middle 5 of the cycle and a second switching time 6 of the transistor in the off state. corresponding to the breaking of the excitation current.
• These switching times DC1 n, DC2n are stored by the microcontroller, and compared to the counting results of clock signals having a third period TCLK3 2048 times smaller than the excitation period Te.
• the counting of the clock signals is carried out in a decreasing direction from 1024 to 0 during the first half of the cycle, and in the increasing direction in the second half 2 of the cycle, from 0 to 1024.
• FIG. 1d The time evolution of the PWM counting and down counting results is shown in FIG. 1d: it is similar to the well-known triangular waveforms of analog switching regulators.
• the excitation current is set, that is to say that the control pulse EXC of the Control transistor is set to logic level 1, as shown in the timing diagram of Figure 1e.
• the calculated switching times DC1 n, DC2n are compared, in the same way as in the first mode, with the results of the counting of clock signals having a third period TCLK3 2048 times smaller than the period of excitement
• clock signals are always counted in the increasing direction in the half-cycles 1, 2.
• the counting of the clock signals is carried out in the increasing direction from 0 to 1024 during the first half of the cycle, and also in the increasing direction in the second half 2 of the cycle, from 0 to 1024.
• the excitation current is established, that is to say that the control pulse EXC of the control transistor is set at logic level 1, as shown in the timing diagram of Figure 2e, and when the result of the second count during the second half cycle 2 is equal to the second switching delay DC2n (at point D), the excitation current is cut off, that is to say that the control pulse EXC of the control transistor is set to logic level 0.
• the control pulse EXC therefore changes level only once per half-cycle, that is to say that its period Te is always the period T of the control cycle, and not the period of the PWM saw teeth.
• the method according to the invention therefore also makes it possible to reduce the phase delay ⁇ (f) by a factor of practically 2 without modifying the switching frequency.
• This switching frequency is preferably between 100 Hz and 350 Hz.
• the regulation method according to the invention therefore provides a regulation bandwidth which corresponds to switching frequencies of between 200 Hz and 700 Hz, without requiring the implementation of a technology that supports high operating temperatures (200 ° C. or more), and / or cooling systems of the electronics, especially water, because of the high losses occurring at these frequencies.
• the regulating device 7.8 adapted to the implementation of the regulation method according to the invention to a rotating electrical machine operating as a generator has the advantage of being little different existing devices.
• This regulating device 7,8 essentially comprises two parts 7,8: a control circuit 7 constituted by an ASIC (specific application integrated circuit), and a power electronics 8 comprising MOSFET transistors 9 (solid state transistor). isolated grid field) control of the excitation current + EXC 1 -EXC applied to the excitation winding 10.
• ASIC specific application integrated circuit
• MOSFET transistors 9 solid state transistor
• the control ASIC 7 comprises in particular:
• microcontroller 11 comprising a real-time clock system 12 and instruction sequences 13 implementing the method according to the invention
• an analog-digital converter 14 intended to acquire samples of the DC voltage B + produced by the machine
• the reference value of the regulation loop is preferably fixed via an interface circuit 17 with the LIN standard network (local interconnection network).
• the real-time clock system 12 supplies the clock pulses CLK1, CLK2 of different periods T, TCLK2, TCLK3 used by the ASIC circuit 7, as well as the interrupt signals IRQ of the microcontroller 11.
• the duration modulated pulse generator EXC specifically comprises a 10-bit binary up-down counter 18, whose evolution of the count value, contained in a counting register, generates a double ramp that a comparator compares to the value of a DC switching delay stored by the microcontroller 11 in a memory register.
• the duration-modulated pulse generator 15 EXC alternately comprises a 10-bit binary counter 18 generating a single ramp.
• This method and this regulating device are preferably used in reversible rotating electrical machines, including a wound excitation, when they operate as generators. Thanks to the regulation device 7, 8 according to the invention, an alternator-starter thus sees its dynamic regulation significantly improved when it operates as an alternator, without this resulting in an increase in the power dissipated by switching in the transistors 9 power because the usual chopping frequency is retained. It goes without saying that the invention is not limited to the only preferred embodiments described above.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Eletrric Generators (AREA)
• Control Of Ac Motors In General (AREA)

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• 2006
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• 2007
  • 2007-09-26 WO PCT/FR2007/052009 patent/WO2008065286A1/fr active Application Filing
  • 2007-09-26 US US12/443,201 patent/US8446131B2/en active Active
  • 2007-09-26 EP EP07823854A patent/EP2095499A1/de not_active Ceased
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