Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
  • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
  • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
  • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M7/53—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M7/537—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
  • H02M7/5387—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/16—Modifications for eliminating interference voltages or currents
  • H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches
  • H03K17/165—Modifications for eliminating interference voltages or currents in field-effect transistor switches by feedback from the output circuit to the control circuit
  • H03K17/166—Soft switching
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
  • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
  • H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
  • H03K17/6871—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor
  • H03K17/6872—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor using complementary field-effect transistors

Definitions

• the invention relates to a circuit arrangement and a method for driving an electrical load, for example, controlled by a control circuit electronic switch in bridge circuit, with which an electric motor of a battery-operated elec- rokleigentrelis is operated.
• Such a circuit arrangement is described in DE 10 2005 059 571. From DE 102 46 520 A1 a circuit arrangement and a method for driving an oscillating electric motor of a battery-powered small electrical appliance by means of a bridge circuit is also known. If the small electrical appliance is operated, for example, with a Li-ion accumulator, and the electronic switches of the bridge circuit are controlled by a control circuit either with a "low” level or a "high” level, the supply voltage can strongly break when the electronic switches are switched over or even more than double, since a Li-ion accumulator has a large compared to other accumulators parasitic inductance, which induces a correspondingly large backlash in current changes.
• this object is achieved by a circuit arrangement which has at least one electronic switch and a control circuit which switches the electronic switch from the non-conductive state to the conductive state and / or conversely that the temporal changes of the flowing current are relatively small.
• a circuit arrangement which has at least one electronic switch and a control circuit which switches the electronic switch from the non-conductive state to the conductive state and / or conversely that the temporal changes of the flowing current are relatively small.
• the relatively large parasitic inductance of a Li-ion rechargeable battery used for power supply can not generate excessive counter-voltages, so that, for example, a microcontroller used as a control circuit can be supplied directly from the accumulator with electricity, ie dispensed, for example, capacitors for smoothing the voltage of the accumulator can be.
• the circuit arrangement is preferably intended for electric toothbrushes or electric razors, which have as drive an oscillating electric motor or linear motor and are operated with a Li-ion accumulator, and is characterized by low circuit complexity.
• large temporal changes in the flowing current can not only generate undesirably large reverse voltages due to the relatively large parasitic inductance of a Li-ion battery used for the power supply, but also, of course, because of the inductance of the electrical load controlled by the circuit arrangement.
• the load is an inductive load, the method according to the invention is applied at least when the current flowing through the load is switched off.
• the control circuit switches the / the electronic switch (s) in at least two steps from the conductive state to the non-conductive state and / or vice versa, for example, the level at the control terminal of the control circuit or at the control terminal of the electronic switch of Low “via” Open “to” High “or from” High “via” Open “to” Low “.
• the method according to the invention can preferably be realized in that the control terminal of the control circuit can be switched either as an input (“high impedance”) or as an output (“low” or “high”) ("tristate "), and for switching the electronic switch from the conducting state to the non-conducting state and / or conversely the control connection of the electronic switch from" low "to” high impedance "to” high “or from” high “to” high impedance " is switched to "low”.
• the control circuit carries out the second step, i. switching from "high impedance” to "high” or “low” only after the electronic switch has changed its state ("conductive” or "non-conductive”).
• the control circuit controls the electrical load by four electronic switches in bridge circuit, and the load is arranged in the transverse branch of the bridge circuit
• the control circuit has control terminals for the four electronic switches.
• the control terminal for the first electronic switch is connected via a series circuit of a first capacitor and a first resistor to the control terminal for the fourth electronic switch
• the control terminal for the third electronic switch is connected via a series connection of a second capacitor and a second resistor connected to the control terminal for the second electronic switch.
• the first and fourth electronic switches are connected to one end of the electrical load
• the second and third electronic switches are connected to the other end of the electrical load.
• the inventive circuit arrangement shown in the figure includes an accumulator A, which has a parasitic inductance L. Further, a bridge circuit is present, which has four transistors V1, V2, V3, V4, and in the transverse branch of an electric motor M or another electrical load is arranged.
• the four transistors V1, V2, V3, V4 are MOS-FETs, each having a protective diode in a conventional manner. They can be controlled by a control circuit uC, which for this purpose has four control connections, each of which can assume the states “high impedance" (input) or "low” or “high” (output) "tristate".
• the control circuit uC is supplied directly from the accumulator A with power.
• the first V1 and third transistors V3 are n-channel MOS FETs whose source terminals are connected to the negative pole of the battery A; the second V2 and fourth transistors V4 are p-channel MOS FETs, whose source terminals are connected to the positive pole of the accumulator A.
• the drain terminals of the first V1 and fourth MOS-FETs V4 are connected to the one end of the motor M, and the drain terminals of the second V2 and third MOS-FETs V3 are connected to the other end of the motor M.
• the gate terminals of the four transistors V1, V2, V3, V4 are each connected via a gate resistor Rg to one of the four control terminals of the control circuit uC.
• the gate resistors Rg serve to limit the total current flowing in driving the transistors into the control means. They may also be omitted if the control circuit is designed for correspondingly higher currents.
• the source terminals of each transistor are connected via a respective pull-up / pull-down resistor Rp and the associated gate resistor Rg to the gate terminal of the respective transistor.
• the control terminal for the first transistor V1 is connected via a series circuit of a first resistor R1 and a first capacitor C1 to the control terminal for the fourth transistor V4.
• the control terminal for the third transistor V3 is connected via a series circuit of a second resistor R2 and a second capacitor C2 to the control terminal for the second transistor V2.
• the circuit arrangement In the initially considered starting situation, the circuit arrangement is in a state in which there is a "low" potential at the control terminals for the fourth V4 and the first transistor V1, and at the control terminals for the second V2 and the third transistor V3 a "high" potential prevails.
• the fourth V4 and the third transistor V3 is turned on, whereas the first V1 and the second transistor V2 block so that a current flows through the motor M from the accumulator A via the fourth V4 and the third transistor V3.
• the circuit arrangement is now to be switched to the state in which the current flows through the motor M in the reverse direction, ie from the accumulator A via the second V2 and the first transistor V1. This switching, ie switching off the currently flowing current and then switching on a current in the opposite direction, will be explained below.
• the charging of the capacitor C1 causes a further increase in the voltage at the gate of the fourth transistor V4, and thus further discharging the Miller capacitance of the fourth transistor V4.
• the gate-source voltage reaches approximately the same value as the drain-source voltage at a time T2> T1
• the fourth transistor V4 goes into its off state, and the Miller capacitance drops to a comparatively small value.
• the voltage at the gate of the fourth transistor V4 then continues to increase, the time constant of this voltage change is now hardly determined by the Miller capacitance of the fourth transistor V4 but mainly by the capacitance of the first capacitor C1 and the sum Rp + R1.
• the control circuit uC switches the control terminal for the fourth transistor V4 from "high impedance" to "high", whereby the switching off of the fourth transistor V4 is terminated.
• a soft turn off the fourth transistor V4 so that the temporal change of the flowing current is so small that the battery voltage of which is hardly affected.
• the turning off of the third transistor V3 may be timed parallel to the turning off of the fourth transistor V4.
• the third transistor V3 is only turned off when only a small or no current flows more, ie with a time delay for turning off the fourth transistor V4.
• the switching off of the third transistor V3 can be carried out by the same method as described above with reference to the fourth transistor V4. However, if only a small or no current flows through the third transistor V3, this can also be turned off “hard” by the control circuit uC directly switches the associated control terminal from "high” to "low", without causing significant interference voltages , By turning off the third transistor V3, the second capacitor C2 is charged.
• the first transistor V1 is turned on, and the third transistor V3 remains initially turned on, i. the motor M is short-circuited via the first V1 and third transistor V3, as described in DE 102 46 520 A1.
• the inductance of the motor M even after switching off the fourth transistor V4 still flowing through the motor M short-circuit current is consumed, and can not flow through the protective diodes of the first V1 and second transistor V2 in the battery.
• the efficiency of the circuit arrangement is improved and prevents the parasitic inductance of the accumulator induces interference voltages. Only when practically no more current flows through the motor M, the third transistor V3 is turned off.
• the second transistor V2 can be turned on by the control circuit uC the associated control terminal directly from “high” to “low” switches, so now on the first V1 and second transistor V2, a current can flow in the reverse direction through the motor M, where because of the inductance of the motor, the time change of the current when switching on the second transistor V2 is sufficiently small.
• the turning on of the first V1 and second transistors V2 occurs only after the turning off of the third V3 and fourth transistor V4 to allow a current to flow in the reverse direction through the motor M
• the first transistor V1 and the second transistor V2 is turned on, wherein the first transistor V1 can also be turned on "hard” by the control circuit uC directly switches the associated control terminal from "low” to "high", without causing appreciable interference voltages.
• the first capacitor C1 is discharged.
• the second transistor V2 is turned on, which can also be done "hard” when the electrical load is an inductive load.
• the switching off of the current flowing through the motor M and the second V2 and the first transistor V1 is carried out as described above with reference to the switching off of the current flowing through the fourth V4 and third transistor V3.
• the control circuit switches its control terminal, which is connected to control the electronic switch either as an input (“high impedance”) or as an output (“low” or “high”) can be ("tristate"), in a first step from “low” to “high impedance” and only in a second step to “high” or in a first step from "high” to "high impedance” and only in one second step to "low".
• the time interval between the first step and the second step is matched to the Miller capacitance of the electronic switch by suitably dimensioning a circuit of the electronic switch containing at least one resistor and a capacitor, and is preferably fixed, the circuit in the case of the bridge circuit described above is formed of the resistors Rp, Rg, R1, R2 and the first C1 and second capacitor C2.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Direct Current Motors (AREA)
• Electronic Switches (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38582021

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (4)

Citations (4)

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• 2006
  • 2006-06-30 DE DE102006030821A patent/DE102006030821A1/de not_active Withdrawn
• 2007
  • 2007-06-20 CN CN2007800236120A patent/CN101479939B/zh active Active
  • 2007-06-20 JP JP2009516945A patent/JP5405299B2/ja active Active
  • 2007-06-20 EP EP07764721.2A patent/EP2036202B1/de active Active
  • 2007-06-20 WO PCT/EP2007/005396 patent/WO2008000373A1/de not_active Ceased
  • 2007-06-20 RU RU2009102983/07A patent/RU2420858C2/ru not_active IP Right Cessation
  • 2007-06-20 US US12/306,169 patent/US8138705B2/en active Active

Patent Citations (4)

Non-Patent Citations (1)

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