WO2010022748A1 - Module d’alimentation - Google Patents

Module d’alimentation Download PDF

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Publication number
WO2010022748A1
WO2010022748A1 PCT/EP2008/006987 EP2008006987W WO2010022748A1 WO 2010022748 A1 WO2010022748 A1 WO 2010022748A1 EP 2008006987 W EP2008006987 W EP 2008006987W WO 2010022748 A1 WO2010022748 A1 WO 2010022748A1
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WO
WIPO (PCT)
Prior art keywords
power supply
supply module
input
power
biasing
Prior art date
Application number
PCT/EP2008/006987
Other languages
English (en)
Inventor
Juergen Gewinner
Peter Herkel
Marvin Dehmlow
Gianfranco Giannini
Original Assignee
Otis Elevator Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Otis Elevator Company filed Critical Otis Elevator Company
Priority to PCT/EP2008/006987 priority Critical patent/WO2010022748A1/fr
Publication of WO2010022748A1 publication Critical patent/WO2010022748A1/fr

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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
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc 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
    • H02M7/217—Conversion of ac power input into dc 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
    • H02M7/219—Conversion of ac power input into dc 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 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc 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
    • H02M7/217—Conversion of ac power input into dc 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
    • H02M7/219—Conversion of ac power input into dc 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 in a bridge configuration
    • H02M7/2195—Conversion of ac power input into dc 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 in a bridge configuration the switches being synchronously commutated at the same frequency of the AC input voltage
    • 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
    • H02M1/0083—Converters characterised by their input or output configuration
    • H02M1/0085—Partially controlled bridges

Definitions

  • the invention relates to a power supply module and to a people conveyor module comprising a power supply module.
  • DC supply circuits including diode bridges, also often referred to as bridge rectifiers, are well-known in the art.
  • diode bridges convert an input voltage of arbitrary polarity into an output voltage of a single polarity.
  • the most common application of these diode bridges is to convert an alternating current (AC) from a standard power outlet or from a transformer, such as power line transformer, into a direct current (DC) to be supplied to a device that operates with a single polarity input voltage.
  • AC shall hereinafter not be limited to describing periodic, wave-shaped voltages or currents, but any voltages or currents that have a changing polarity over time. However, voltages/currents de- noted with AC commonly have a sine shape.
  • a bridge circuit generally has four terminals, two input terminals and two output terminals. Each input terminal is connected to each output terminal through a leg, yielding four legs in total.
  • the common diode bridge comprises one diode, usually a silicon diode, per leg oriented in a way that current can only flow in one direction from a first output terminal to a second output terminal, regardless of the polarity of the input voltage, as is well-known in the art.
  • diode bridges are used for a variety of DC driven components, for example elevator brakes, elevator call buttons, and elevator lighting. Said diode bridges dissipate a large amount of electric power which reduces the overall efficiency of the elevator system. Additionally, the dissipated power produces heat, which has to be compensated for by accord- ing cooling means, which becomes more and more problematic and costly in modern, highly integrated elevator systems.
  • Exemplary embodiments of the invention include a power supply module for providing electric power to a DC driven component, said power supply module comprising a bridge rectifier, wherein said bridge rectifier comprises an AC in- put, a bridge circuit, a DC output to be coupled to said DC driven component, and an AC phase detection circuit coupled to said AC input and adapted to output a phase control signal according to at least the polarity of said AC input, wherein said bridge circuit comprises at least two transistors coupled to said phase control signal.
  • Figure 1 shows a schematic of an exemplary power supply module in accor- dance with the present invention, wherein the bridge circuit comprises two transistors.
  • FIG. 2 shows a schematic of another exemplary power supply module in accordance with the present invention, wherein the bridge circuit comprises four transistors.
  • FIG. 3 shows a schematic of yet another exemplary power supply module in accordance with the present invention, wherein the AC phase detection circuit receives a feedback signal indicative of the current supplied to the DC driven component.
  • FIG. 1 shows a power supply module in accordance with an embodiment of the present invention.
  • the power supply module comprises two input termi- na!s, also referred to as input nodes: a first input node 11 and a second input node I2.
  • An AC voltage source denoted AC
  • the voltage input AC common- Iy is a secondary winding of a transformer supplying an AC voltage in the order of 10-30V.
  • the primary winding of said transformer is commonly coupled to the power supply voltage of 110-230V AC, but may also be coupled to another AC voltage available in the people conveyor environment, such as a 400V AC voltage.
  • the invention shall by no means be limited to a particular embodiment or magnitude of the input voltage AC.
  • the power supply module also comprises two output terminals, also referred to as output nodes: a first output node 01 and a second output node 02.
  • a DC driven load is coupled between the two output nodes 01 and 02.
  • the DC driven load comprises a capacitive component C L and a resistive component R L , also referred to as the load capacitor C L and the load resistor R L .
  • typical DC driven loads are brakes, electromagnetic actuators, lighting devices, relays, user command buttons, door drives, electric motors, load sensors, or further electric cir- cuitry.
  • some of these loads can be characterized by a resistive and a capacitive component, as shown in the exemplary embodiment of Figure 1.
  • the capacitor shown in the exemplary embodiment of Fig. 1 is no load capacitor, but a smoothing capacitor disposed between the output nodes 01 and 02 to make the voltage supplied to the load more constant and less volatile, as is well known in the art.
  • Typical operating conditions and component values in the field of elevators are as follows.
  • the DC voltage supplied to the DC load is typically in the order of 10-60 V.
  • the current supplied to the DC load is commonly in the order of 1-10 A.
  • the resistive component is generally around 1-60 ⁇ .
  • a typical smoothing capacitor has 1000-10000 ⁇ F.
  • the actual power supply module converting the AC input voltage received at input nodes 11 and I2 into a DC output voltage supplied to a DC driven load at output nodes 01 and 02 is described hereinafter.
  • the two input nodes 11 and I2 and the two output nodes 01 and 02 are connected by four legs, i.e. each input node is coupled to each output node via one leg.
  • These four legs comprised of electrically conductive material, such as wires, and additional circuit elements, constitute a bridge circuit.
  • a first diode D1 is connected between second input node I2 and first output node 01, with the anode of the first diode D1 being connected to second input node I2 and the cathode being connected to first output node 01.
  • a second diode D2 is connected between first input node 11 and first output node 01, with the anode of the second diode D2 being connected to first input node 11 and the cathode being connected to first output node 01.
  • a power MOSFET is a specific type of metal oxide semiconductor field-effect transistor (MOSFET), designed to handle large power. When operated in an on-state, power MOS- FETs commonly have a small drain to source resistance RD S _ O N, making them efficient switches in high power applications.
  • MOSFET metal oxide semiconductor field-effect transistor
  • Another specific feature of modern power MOSFET devices is a body diode between source and drain of the transistor, with the body diode comprising a PN junction. In n-channel power MOS- FETs, the source is the anode and the drain is the cathode of the body diode.
  • said body diodes are included into the symbols for the power MOSFET devices throughout the Figures. As is shown by the symbols used for the power MOSFET devices, the body diode is in parallel with the transistor channel between drain and source.
  • a first power MOSFET T1 is connected between second output node 02 and first input node 11, with the source of first power MOSFET T1 being connected to second output node 02 and the drain of first power MOSFET T1 being connected to first input node M.
  • a second power MOSFET T2 is connected be- tween second output node 02 and second input node I2, with the source of second power MOSFET T2 being connected to second output node 02 and the drain of second power MOSFET T2 being connected to second input node I2.
  • First and second power MOSFETs T1 and T2 of the exemplary embodiment are n-channel enhancement MOSFET devices. It is apparent to a person skilled in the art that, with an according amendment of the module structure and the bi- asing, which will be described below, p-channel devices or depletion type transistors or other suitable transistor devices may be used in a similar manner.
  • the gate of the first power MOSFET T1 is connected to a first biasing node B1, which is part of a first biasing path that originates at first output node 01 and terminates at second output node 02.
  • a first switching element S1 which is responsive to a control signal NH, as described below.
  • a first resistor R1 Between first biasing node B1 and second output node 02 there is provided a first resistor R1.
  • a sec- ond biasing path originating at first output node 01 and terminating at second output node 02 is configured in an according manner: a second switching element S2 responsive to another control signal PH is connected between first output node 01 and a second biasing node B2, which in turn is connected to the gate of second power MOSFET T2, and the second biasing node B2 is fur- ther connected to second output node 02 through a second resistor R2.
  • the power supply module further comprises a phase control circuit, also referred to as phase detection circuit and denoted Phase Control throughout the Figures.
  • the phase detection circuit is disposed between the first input node 11 and the second input node I2.
  • the phase detection circuit outputs two signals, a control signal PH and a control signal NH.
  • the control signal PH is set to a logic 1-value when a positive half wave of input voltage AC is present at the power supply module inputs, and is set to a logic 0-value for a negative half wave.
  • the control signal NH is set to a logic 1-value when a negative half wave of the AC voltage is present at the power supply module inputs, and is set to a logic revalue for a positive half wave.
  • positive and negative are defined in this exemplary embodiment with regard to the voltage from first input node 11 to second input node I2, i.e. the potential at first input node 11 being greater than the potential at second input node I2 is defined as a positive input.
  • positive half wave and negative half wave are based on the assumption that a wave-like sine-shaped AC signal is supplied to the power supply module at the voltage input AC.
  • the control signal PH indicates that first input node 11 has a greater potential than second input node I2 and the control signal NH indicates that second input node I2 has a greater potential than first input node 11, regardless of the voltage course over time of voltage input AC.
  • control signal PH and NH may in other embodiments not be simply the polarity of the voltage input. It can be thought of determining a threshold value in order to prevent false signal setting.
  • the control signal PH may only be set to a logic 1 -value when the potential difference between the first input node 11 and the second input node I2 exceeds a predetermined posi- tive amount.
  • control signals PH and NH may be substituted by one signal only that has predefined states which correspond to the respective polarities of the AC input signal. Accordingly, the processing of such a signal in the switching elements S1 and S2 would have to be adjusted accordingly.
  • the phase detection circuit comprises two light-emitting diodes (LEDs, not shown), which are connected in parallel and have different orientation.
  • the anode of a first LED is connected to the first input node 11, whereas the cathode of a second LED is connected to the first input node 11.
  • a phase control circuit biasing resistor (not shown). I.e. one end of the phase control circuit biasing resistor is connected to the second input node I2, whereas the other end is connected to the cathode of the first LED and the anode of the second LED.
  • the biasing re- sistor may be used to adjust the sensitivity of the LEDs, depending on the magnitude of the input AC voltage. By making the phase control circuit biasing resistor as large as possible, given a desired sensitivity of the LEDs, the current through the phase control circuit and the associated losses are minimized.
  • the first and the second switching elements S1 and S2 each comprise a photo tran- sistor (not shown). Accordingly, the first LED in the phase control circuit and the photo transistor in the second switching element S2 constitute a first opto- coupler, with the control signal PH being an optical signal. Similarly, the second LED and the photo transistor of the first switching element S1 constitute a second opto-coupler, with the control signal NH being an optical signal.
  • phase detection circuit and the switching elements have the advantage of galvanicly isolating phase detection and biasing of the bridge circuit, while ensuring a very reliable control of the bridge circuit.
  • Other coupling means be- tween the phase control circuit and the switching elements, such as transistor stages, may be thought of and may be suitable for various applications of the invention.
  • the operation of the exemplary embodiment of the invention of Figure 1 is de- scribed as follows. It is assumed that the input voltage AC is supplied by a secondary winding of a transformer (not shown) with alternating polarity, such as a sine shape. At a first point in time, the potential of first input node 11 is larger than the potential of second input node I2. It is not of importance which potential the two input nodes have with regard to a ground potential.
  • the positive in- put voltage sets the first LED in the phase control circuit into a conductive state and gives rise to a current flow through that first LED and the phase control circuit biasing resistor from first input node 11 to second input node I2. As a consequence, the first LED emits light, which corresponds to the control signal PH having a logic 1-value.
  • the photo transistor Since the first LED is optically coupled to the photo tran- sistor in the second switching element S2, said photo transistor becomes conductive, i.e. the switch of the second switching element S2 is closed, and the second biasing node B2 is brought to the potential of the first output node 01.
  • the resulting current flow through the second biasing path and the second resistor R2 gives rise to a potential difference between second biasing node B2 and second output node 02, which are the gate and the source of the second power MOSFET T2, respectively. This potential difference sets the second power MOSFET T2 into a conducting state.
  • the second biasing resistor R2 is chosen to have a high resistance in order to keep the current flow through the second biasing path and the associ- ated power dissipation to a minimum.
  • Exemplary values for the resistors used are 10-20 k ⁇ .
  • the low drain source resistant R DS _ ON that is present in second power MOSFET T2 in the on-state results in a voltage drop across T2, which is only a fraction of a diode voltage drop at common operating conditions.
  • Common operating conditions have a current flow of 1-10A, which results in a drain source voltage drop across second power MOSFET T2 that is only about 10% of a common diode voltage drop.
  • the power supply module of Figure 1 operates in an according manner when a negative voltage is supplied to the input nodes 11 and I2, i.e. when second in- put node I2 is at a higher potential than first input node 11.
  • the exemplary embodiment of Figure 1 is particularly advantageous when loads with a capacitive component are present at the output of the power supply module.
  • the two diodes D1 and D2 prevent a current flow back into the power supply module from the capacitive load at all operating conditions, regardless of the voltage supplied by AC to the input nodes 11 and I2. A bridge short condition is therefore prevented at all times.
  • the two power MOSFETs T1 and T2 ensure that a minimal amount of waste power is generated in the remaining two legs of the bridge circuit. Consequently, the bridge circuit of the exemplary embodiment of Figure 1 produces only 50-60% of the waste power produced by conventional diode bridges at common operating conditions.
  • Figure 2 shows a power supply moduie in accordance with another embodiment of the present invention.
  • the output nodes 01 and 02 of the power supply module are coupled to a load consisting of a resistive component R L and an inductive component L L , also re- ferred to as load resistor R L and load inductor L L , respectively, which are connected in series.
  • the two legs of the bridge circuit comprising the power MOS- FETs T1 and T2 as well as their associated biasing paths are structured identically as in the embodiment of Figure 1.
  • the phase detection circuit of Figure 2 again denoted Phase Control, also corresponds to the phase control circuit of Figure 1 and also has two control signals PH and NH as its outputs.
  • Phase Control also corresponds to the phase control circuit of Figure 1 and also has two control signals PH and NH as its outputs.
  • a third power MOSFET T3 is provided between second input node I2 and first output node 01.
  • the source terminal of the third power MOSFET T3 is connected to the second input node I2, its drain terminal is connected to the first output node 01, and its gate is connected to a third biasing node B3, which will be dis- cussed in detail below.
  • a fourth power MOSFET T4 is provided between first input node 11 and first output node 01.
  • the source of the fourth power MOS- FET T4 is connected to the first input node 11, its drain is connected to the first output node 01, and its gate is connected to a fourth biasing node B4.
  • the biasing networks for the third and the fourth power MOSFETs T3 and T4 are described as follows.
  • the first output node 01 is connected to a fifth biasing node B5 via a first biasing diode DB1, with the anode of the first biasing diode DB1 being connected to first output node 01 and the cathode of the first biasing diode DB1 being connected to the fifth biasing node B5.
  • Fifth biasing node B5 is further connected to second input node I2 via a first biasing capacitor CB1.
  • a third biasing path having a third biasing node B3 is provided between the fifth biasing node B5 and the second input node I2.
  • a third switching element S3 controlled by control signal NH is disposed between fifth biasing node B5 and third biasing node B3.
  • a third resistor R3 is disposed between third biasing node B3 and second input node I2.
  • the first output node 01 is furthermore connected to a sixth biasing node B6 via a second biasing diode DB2, with the anode of the second biasing diode DB2 being connected to first output node 01 and the cathode of the second bi- asing diode DB2 being connected to the sixth biasing node B6.
  • Sixth biasing node B6 is further connected to first input node 11 via a second biasing capacitor CB2.
  • a fourth biasing path having fourth biasing node B4 is provided between sixth biasing node B6 and first input node II.
  • a fourth switching element S4 controlled by control signal PH is disposed between sixth biasing node B6 and fourth biasing node B4.
  • a fourth resistor R4 is disposed between fourth biasing node B4 and first input node 11.
  • the fourth resistor R4 is chosen to minimize the biasing current flow through the fourth biasing path, while providing a desired voltage difference between fourth biasing node B4 and first input node 11.
  • the closing of second switching element S2 leads to second power MOSFET T2 being in a conductive state, as described with regard to Figure 1.
  • a conductive path is formed from first input node 11 through fourth power MOSFET T4, load resistor R L , load conductor U and second power MOSFET T2 to second input node I2. In this man- ner, a current having the desired flow direction is supplied to the load.
  • second biasing capacitor CB2 is discharged through fourth resistor R4.
  • second biasing capacitor CB2 and fourth resistor R4 have to be dimen- sioned in a way to ensure that the second biasing capacitor CB2 is not fully discharged before the polarity at the voltage input AC changes.
  • the second biasing capacitor CB2 is recharged through the second bi- asing diode DB2.
  • Second biasing capacitor CB2 can therefore also be seen as a charge pump supplying the needed voltage conditions, also denoted boost voltage, to the fourth biasing path.
  • the charge pump ensures that the sixth biasing node B6 maintains an appropriate potential with regard to input nodes 11 and I2, which in turn ensures appropriate switching of power MOSFET T4.
  • the third switching element S3 will be closed for a negative input voltage supplied by AC, with the first biasing capacitor CB1 providing for voltage conditions at third biasing node B3 to switch third power MOSFET T3 while being discharged.
  • First biasing capacitor CB1 is accordingly recharged through first biasing diode DB1 when a positive voltage is present at the voltage input AC.
  • the exemplary embodiment of the invention of Figure 2 is particularly suited for power module applications supplying current to loads that have no or only a small capacitive component, as the following problem arises from capacitive loads.
  • a capacitive component may be charged up to the potential difference between first input mode 11 and second input node I2 at their peak potential difference. This could lead to first output node 01 being on a higher potential than the positive input node at certain points in time during the operation of the power supply module, for example right after a polarity change at the input. If the power MOSFET between the positive input node and the first output node 01, which is at a higher potential, was then set into a conductive state, current would flow from the first output node 01 to the positive input node.
  • the third and fourth power MOSFETs T3 and T4 are not able to block a current flow from first output node 01 to said momentarily positive input node, as such a current flow is in the drain to source direction of the power MOSFET devices in the ex- emplary embodiment.
  • a load capacitor could give rise to a backflow of current opposing the desired DC current direction.
  • Such a scenario also referred to as a bridge short circuit, is potentially damaging to the bridge circuit and the associated circuit elements. Therefore, exemplary load applications of the power supply module of Figure 2 are mainly electromagnet- ic actuators that work well without the smoothing operation of a smoothing capacitor.
  • Such applications comprise a DC brake, such as an elevator brake, with the inductive load being the brake coil of said DC driven brake.
  • a DC brake such as an elevator brake
  • Exemplary DC brakes operate with DC voltages of 12 V to 110 V and power consumptions of 30 W to 300 W.
  • voltages of up to 1000 V may be used, which may require multiple transistors in parallel in each leg of the bridge circuit to keep the currents through the transistors at an acceptable level.
  • Typical elevator weights are in the range of 600 kg to 5000 kg. The invention shall, however, by no means be limited to any of these exemplary values.
  • the current supplied to the load by the power supply module of Figure 2 flows through two power MOS- FETs, and not through two diodes.
  • the two voltage drops associated with the diodes of the common diode bridge rectifier are replaced with significantly smaller voltage drops present between drain and source of the power MOSFETs and proportional to their drain source on-resistance R DS .
  • the waste power generated in the bridge circuit of Figure 2 is only about 0-20% of the waste power generated in a diode bridge. More precisely, the waste power is only about 10% of the waste power of the prior art.
  • Another embodiment is similar to the embodiment of Figure 2.
  • the only differences to the embodiment of Figure 2 is that the first biasing diode DB1, the first biasing capacitor CB1, and the path connecting the first output node 01 and the second input node I2 through fifth biasing node are not present.
  • the terminal of the third switching S3, which was connected to fifth biasing node B5 in the embodiment of Figure 2, is connected to sixth biasing node B6 for the alternative embodiment. In this way, the number of components can be reduced, while still ensuring efficient control of the third and fourth power MOSFETs T3 and T4.
  • FIG. 3 shows another power supply module in accordance with an embodiment of the present invention.
  • the load is connected between a first output node 01 and an alternate second output node 02' of the power supply module of Figure 3.
  • the load comprises a resistive component R L , an inductive component L L and a capaci- tive component C L .
  • These load components are also referred to as the load resistor R L , the load inductor L L and the load capacitor C L .
  • the load resistor R L and the load inductor L L are connected in series, with the load capacitor C L being connected in parallel with that se- ries circuit.
  • phase control circuit comprises additional functionality, as will be described below.
  • the load comprises a capacitive component C L
  • operating the power supply module in the same manner as described with respect to Figure 2 would lead to the above-described problem of current backflow into the bridge circuit at certain operating conditions.
  • such current opposing the desired DC current supply direction is potentially harmful to the bridge circuit components.
  • the load design may rely on the assumption of cur- rent only flowing in one desired direction and may not be able to reliably deal with current flow in the opposing direction.
  • the power supply module of the exemplary embodiment of Figure 3 additionally comprises a current feedback circuit.
  • the current feedback circuit of the exemplary embodiment of Figure 3 comprises comparing means, particularly an operational amplifier Comp, and a shunt resistor R s .
  • the positive power supply terminal of the operational amplifier Comp is connected to the first output node 01, the negative power supply terminal is connected to the second output node 02.
  • a reference voltage V_REF is sup- plied to the non-inverting input of the operational amplifier Comp.
  • the inverting input of the operational amplifier Comp is connected to the alternate second output node 02'.
  • the alternate second output node 02' represents the second output node of the power supply module as seen from the load.
  • above-mentioned shunt resistor R s is provided for current measuring purposes.
  • the output of the operational amplifier Comp is connected to the phase control circuit, with the control signal Gates_Off, which is output by the operational amplifier Comp, being supplied to the phase control cir- cuit as an additional input.
  • the current feedback circuit works as follows.
  • the current that is supplied to the load by the power supply module flows through shunt resistor Rs-
  • shunt resistor R 3 should be chosen as small as possible in order to minimize power losses associated with the feedback circuit.
  • One end of the shunt resistor R 3 is connected to the negative power supply of the operational amplifier Comp and the other end is connected to the inverting input, which results in a voltage being applied to the inverting input of the operational amplifier Comp that is proportional to the cur- rent supplied to the load.
  • This voltage which is indicative of the load current, is compared to the reference voltage V_REF.
  • the voltage signal Gates_Off output by the operational amplifier Comp indicates whether the measured voltage is higher or lower than the reference voltage V_REF. If for example the reference voltage V_REF is set to OV, the con- trol signal Gates_Off indicates, which direction the current supplied to the load flows.
  • 02' to first output node 01 may be used in the phase control circuit to set both output control signals PH and NH to a logic 0-value.
  • This may be implemented by having the control signal Gates_Off control an additional switch that is connected in series with the remaining circuitry in the phase control circuit. For load current flow in the desired flow direction said switch will be closed, whereas it will be open for cur- rent flow opposing the desired flow direction.
  • Both control signals PH and NH having a logic 0-value will result in none of the four power MOSFETs T1, T2, T3, and T4 being in a conductive state, which in turn will result in all current flow through the transistor channels being stopped.
  • the four body diodes of the four power MOSFETs T1, T2, T3, and T4 will form a diode bridge circuit, which will allow continuing rectifying operation while blocking current flow opposing the desired current flow direction.
  • the reference voltage V_REF does not necessarily have to be OV. It may for example be a voltage corresponding to a small positive current flow from first output node 01 to alternate output node 02'. In case the measured voltage falls below said reference voltage, a possible interpretation would be that the current flow through the load is in danger to change polarity. As a precaution, all current flow through the power MOSFET channels could be stopped by setting the control signals PH and NH to a logic 0-value, as discussed above. As an example, the power supply module and the load may be designed in a .way, such that the maximum current for the voltage peak of the AC input voltage is 1OA. Shunt resistor R s and reference voltage V_REF may then be chosen, such that the current flow falling under 1A will result in all four power MOSFET channels being set into a non-conductive state.
  • the body diodes of the four power MOSFETs T1, T2, T3, and T4 still provide for a voltage rectifying operation and a current flow in the desired DC current direction.
  • the bridge circuit then rectifies the AC voltage input and outputs a DC voltage, with the formed current path through the bridge circuit having two diode voltage drops at the two body diodes that are forward biased at that moment. As soon as the potential difference between the first and second input nodes 11 and I2 is bigger than two body diode voltage drops, the current flow through the load will start again.
  • operational amplifier Comp will set the control signal Gates_Off into a state indicating to the phase control circuit that it is safe to set selected channels of the four power MOSFETs T1, T2, T3, and T4 into a conductive state. Accordingly, the body diodes help in reinstalling a low loss bridge circuit operation, which will be reached automatically without any active components.
  • the smoothing capacitor can keep supplying electric energy to the load resistor R L and load inductor L L when the bridge circuit supplies no or little electric energy. Whenever the measured current flow indicates, however, that there is no danger of current flowing back into the bridge circuit, the according power MOSFETs may be switched and the bridge circuit operates with very low power losses.
  • load capacitor CL may be a capacitive ele- ment of a DC driven component or a smoothing capacitor used for making the voltage supplied to the load at output nodes 01 and 02 more constant.
  • the above described rectifying functionality of the body diodes is also advantageous with regard to the embodiments of Figures 1 and 2. Should the control signals PH and NH not correspond exactly to the polarity of the input voltage AC, for example due to the threshold voltages to be exceeded for the operation of LEDs in the phase control circuit or other system considerations, the body diode rectifying serves as a supplement to the power MOSFET channel rectifying.
  • the power supply module embodiment of Figure 3 is particularly advantageous, as it can be used regardless of the connected load. Similar waste power savings as associated with the power supply module embodiment of Figure 2 can still be realized, even though a capacitive load is present. At very low addi- tional complexity and low associated power losses the current to the load can be monitored and fed back to the bridge circuit control circuitry. This allows for an efficient protection of all components of the power supply module and a prevention of all possible problems associated with current backflow into the bridge circuit.
  • Exemplary embodiments of the invention as described above allow for a more efficient DC power supply module, particularly for a reduction of the waste power dissipation and the waste heat generation.
  • the invention further allows for a superior energy efficiency and control system integration.
  • the transistors provided in the bridge circuit of the power supply module according to the invention allow for a significant reduction of the voltage drop associated with the supply current path through the bridge circuit.
  • the voltage drop caused by the transistors' on-resistance is significantly lower than a commonly encountered voltage drop of a diode operated in the forward direction.
  • the phase detection circuit which is coupled directly to the input nodes allows for a very simple, accurate, reliable and low loss control of the transistors which are disposed in the bridge circuit of the power supply module.
  • the claimed structure further allows for a very simple and low cost scheme of the transistor control, which can be designed consisting entirely of passive components.
  • a pow- er supply module is provided that converts an AC input into a DC output with at least the same reliability and accuracy as a diode bridge circuit while dissipating significantly less power.
  • the saved power can be supplied additionally to the load or can be saved at an upstream stage.
  • a longer portion of an input AC voltage may be used at the output of the power supply module.
  • the reduction of dissipated power in the bridge circuit also leads to a reduction of waste heat generated at the power supply module and thus to avoiding bulky heat sinks.
  • the cooling means usually associated with high power rectifying devices can be reduced in size and performance. Therefore, additional power previously needed for the cooling functionality can be saved.
  • the space requirements for the cooling means are reduced as well, which results in a greater integration and a smaller overall size of the power supply module as compared to the prior art. Therefore, a higher package density of controller ele- ments can be achieved, particularly when surface-mounted devices (SMD) are used.
  • SMD surface-mounted devices
  • the power supply module according to the invention may be as expensive or even cheaper than the power supply modules of the prior art, despite the complexity and component cost of the bridge circuit being higher for the present invention. Also, the life span of the components used may be lengthened by making use of the present invention.
  • control signal couples the AC phase detection circuit and the transistors, there is an additional degree of freedom in the circuit design.
  • the control signal is indicative of the polarity of the AC input and allows therefore a very direct control of the transistors.
  • additional factors can be taken into account when producing the control signal, which may in some embodiments lead to an overruling of the pure response to the AC input polarity.
  • custom made control of the bridge circuit such as adaptations to the load conditions, becomes possible.
  • the bridge circuit of the power supply module may comprise in each of the two portions of the bridge circuit that have current flow for different polarities of the AC input a transistor and a diode connected in series.
  • the current supplied to the DC driven component flows through one of the diode and the transistor first, then through the DC driven component, and then through the other element of the transistor and the diode.
  • a series cir- cuit of transistor/diode, DC driven component and transistor/diode is formed.
  • the two diodes - one for each polarity of the AC input - are disposed between the input nodes and the high potential output node, i.e. the current supplied to the DC driven component has to pass the diode first.
  • This embodiment is particularly advantageous, as the diodes block any current flow back towards the input arising from the DC driven component, particularly from a capacitive load component of the DC driven component or a smoothing capacitor.
  • the forward voltage drop in the transistors is very small, ensuring a greatly reduced power dissipation and heat generation in the bridge circuit of the power supply module.
  • the power dissipation of the power supply module can be reduced to 50-60% of the power dissipation of the prior art.
  • the bridge circuit may have four legs and comprise four transistors, with each of the transistors being disposed in one of the four legs.
  • the current supplied to the DC driven component flows for any given polarity of the AC input through one transistor, the DC driven load, and a second transistor. Due to the low forward voltage drop caused by the low on-resistance of the transistors, a minimum amount of waste power and waste heat is generated in the bridge circuit of the power supply module. This allows for a superior overall efficiency of the power supply module, which can be used by providing a lower AC voltage at the input to the power supply module or by passing on more power to the DC driven component.
  • the cooling devices required for keeping the power supply module at an acceptable operating temperature may be reduced in size and performance, which in turn allows for greater system integration and lower power requirements.
  • the power dissipation of the power supply module can be reduced to 5-20%, more particularly to about 10% of the power dissipation of the prior art.
  • the transistors of the power supply module are power MOS- FETs.
  • Power MOSFETs are a type of metal oxide semiconductor field-effect transistors (MOSFET) designed to handle large power.
  • MOSFET metal oxide semiconductor field-effect transistors
  • a commonly used structure for power MOSFETs is the vertical diffused MOS (VDMOS) structure.
  • VDMOS vertical diffused MOS
  • Alter- native structures are apparent to a person skilled in the art.
  • Modern power MOSFETs have the advantage of exhibiting a low resistance, when in an on- state, even when a large current flow is present.
  • the power MOSFET elements are disposed in the bridge circuit in a way such that the current, which is supplied to the DC driven load in the desired direc- tion, flows through the power MOSFET transistors from source to drain.
  • power MOSFETs comprise a so-called body diode from source to drain.
  • This body diode is commonly caused by a connection of the body to the source inherent to the power MOSFET device.
  • power MOSFETs have a diode connected in parallel with their channel.
  • This embodiment is particularly advantageous, as two conductive channels, namely through the body diode and through the channel of the MOSFET device (given an according gate source voltage), are provided.
  • the body diodes provide for a bridge circuit having functionality similar to a conventional diode bridge.
  • the bridge circuit may comprise at least two biasing paths connected to the transistors.
  • Biasing paths have the advantage, as compared to controlling the transistors directly via the phase control signal, that biasing potentials can be applied in a more predictable and stable manner. The additional complexity can be held low, while simple and clean im- plementations can be realized.
  • one biasing path per transistor allows for accurate and efficient control of the biasing paths by the phase control signal and efficient and accurate control of the transistors by the biasing paths.
  • two transistors which are set in a conductive state for a given AC input polarity, may share one biasing path, respectively. This allows for very low additional complexity introduced by the biasing path and a minimum number of circuit elements needed for efficiently controlling the transistors.
  • each of the transistors has a biasing path associated therewith.
  • this embodiment allows for an individually designed biasing path for each one of the transistors, ensuring that the transistors will be controlled accurately by the respective biasing path for all operating conditions expected in the power supply module.
  • each of said biasing paths comprises a switching element.
  • the switching elements allow for providing one of two different electric potentials to the gates of the respective transistors, thereby al- lowing an efficient and accurate switching between the conductive and the non-conductive state of the respective transistors.
  • the implementation of the switching elements and the phase detection circuits as well as the coupling via the phase control signal may be done as a combined system. In this regard, it may be possible that the switching elements are controlled by the phase control signal.
  • phase detection circuit and the switching elements are coupled optically.
  • the circuit elements disposed in the AC phase detection circuit and the switching elements in the biasing paths associated with the tran- sistors may together form opto-couplers, with the circuit elements in the AC phase detection circuit generating optical signals and the switching elements in the biasing paths reacting to optical signals.
  • Such optical coupling has the advantage of galvanically separating the AC phase detection circuit and the biasing paths. Among other advantages this allows for a simple design in order to keep the currents low in these power module portions. This in turn is the basis for making sure that no excessive power loss overhead is produced in circuit portions that have been introduced in addition to the primary supply current paths to and from the load.
  • opto-couplers arbitrary potentials may be coupled, which provides for more freedom in designing the power supply module.
  • the power supply module comprises at least one biasing capacitor connected to at least one of the biasing paths.
  • the biasing capacitor allows for the provision of a charge reservoir, which in turn allows for the provision of necessary biasing node potentials, regardless of the momentary AC input and DC output voltages.
  • the biasing capacitor particularly ensures that the gate source potential sets the transistor into an on-state, independent of the current AC input voltage.
  • the power supply module is adapted to provide electric power to one of a group consisting of a load having a ca- pacitive component and a smoothing capacitor.
  • Adapting the power supply module in a way such that it is possible to couple the power supply module to a capacitive component at the DC output is particularly advantageous, since a wide variety of loads contains capacitive components. Also, many loads, which may not have a capacitive component, require a voltage that is more constant over time than a simply rectified sine wave. This is commonly achieved by a smoothing capacitor at the output, which corresponds to the introduction of a capacitive load component.
  • the power supply module comprises a feedback circuit responsive to the current supplied to the DC driven component and adapted to output a bridge circuit command signal to said phase detection cir- cuit based on said current supplied to said DC driven component.
  • a feedback circuit allows for monitoring of the load current conditions and a timely interaction before the current through the DC driven component changes direction. A change of direction would mean current flowing back into the bridge circuit, as the transistors of the bridge circuit - when in a conductive state - may not be able to block current flow against the desired direction. This is particularly true for MOSFET devices.
  • the phase control signal may in a further embodiment be indicative of the bridge circuit command signal.
  • the bridge circuit command signal generated by the feedback circuit may have an effect on the phase control signal, such that the phase control signal is not purely indicative of the AC input polarity anymore.
  • the polarity of the AC input may not be deducible from the phase control signal anymore.
  • the bridge circuit command signal can accordingly be seen as having an overruling character.
  • the bridge circuit command signal can lead to the phase control signal having a state where none of the transistors of the bridge circuit are in a conductive state. This allows for effective protection of the bridge circuit components from current flow into the bridge circuit against the desired DC current direction.
  • the power supply module is adapted to terminate supplying electric power to the DC driven component when the current supplied to the DC driven component is below a predetermined threshold. This allows for setting a rule when the current supplied to the DC driven component is in a range where it is already harmful to the bridge circuit components or where a further change is potentially damaging to the bridge circuit components. Having a threshold value in place allows for an efficient quantitative control by the feedback circuit.
  • Exemplary embodiments of the invention also include a people conveyor module comprising a power supply module as described above and a DC driven component, wherein the DC driven component is one of the group of components of a people conveyor installation consisting of a brake, a lighting device, a relay, an electric circuit, a user command button, a door drive, an electric motor, and a load sensor, or any combination thereof.
  • DC brakes are contained in the group of electromagnetic actuators present in people conveyors.
  • DC brakes are mainly comprised of inductive and resistive components and work well in the absence of a smoothing capacitor. Relays are also mainly comprised of in- ductive and resistive components.
  • Exemplary people conveyors are elevators, escalators and moving walkways. It could even be thought of using embodiments of the invention to supply power to drive systems of people conveyors.
  • Exemplary values for the components and operating conditions of the power supply module according to the invention are as follows.
  • the input voltage supplied to the AC input of the power supply module may have a peak value of 10-50 V. It is commonly a wave shaped voltage over time alternating in polarity and moving between the positive and negative peak values, which are commonly equal in magnitude. Typical currents range between 1 A and 10 A.
  • a prior art diode bridge would have produced about 14 W of waste heat, when a standard diode forward voltage drop of 0.7 V is assumed.
  • a power supply module according to the invention having two transistors and two diodes in the four legs of the bridge circuit may only produce 50-60% of that waste heat.
  • a power supply module according to the invention having a transistor in all four legs of the bridge circuit may produce less than 20% of that waste heat, more precisely around 10% of the waste heat, associated with a prior art diode bridge.
  • Typical values of the resistive load are between 1 ⁇ and 50 ⁇ .
  • Commonly used smoothing capacitors have 1000 ⁇ F to 10000 ⁇ F.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

L'invention concerne un module d'alimentation destiné à appliquer de la puissance électrique à un composant (RL, CL, LL) piloté en courant continu, lequel comprend un pont de redresseurs, ledit pont de redresseurs comprenant une entrée en courant alternatif (AC), un circuit en pont, une sortie en courant continu (O1, O2) devant être reliée au dit composant piloté (RL, CL, LL) et un circuit de détection de phase alternative (commande de phase) relié à ladite entrée en courant alternatif (AC) et conçu pour fournir en sortie un signal de commande de phase (PH, NH) au moins en fonction de la polarité de ladite entrée en courant alternatif (AC). Le circuit en pont comprend au moins deux transistors (T1, T2, T3, T4) reliés au dit signal de commande de phase (PH, NH).
PCT/EP2008/006987 2008-08-26 2008-08-26 Module d’alimentation WO2010022748A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2008/006987 WO2010022748A1 (fr) 2008-08-26 2008-08-26 Module d’alimentation

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Application Number Priority Date Filing Date Title
PCT/EP2008/006987 WO2010022748A1 (fr) 2008-08-26 2008-08-26 Module d’alimentation

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8804389B2 (en) 2012-02-16 2014-08-12 Linear Technology Corporation Active bridge rectification
US11286131B2 (en) 2015-03-24 2022-03-29 Kone Corporation Energizing circuit of a magnetizing coil of an operational brake, a passenger conveyor, and a method for energizing the magnetizing coil of the operational brake of a passenger conveyor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3434034A (en) * 1967-03-14 1969-03-18 Hewlett Packard Co Universal ac or dc to dc converter
JPS63190561A (ja) * 1987-01-29 1988-08-08 Nec Corp 整流回路
US5268833A (en) * 1991-05-14 1993-12-07 U.S. Philips Corporation Rectifier circuit including FETs of the same conductivity type
WO1996001003A1 (fr) * 1994-06-29 1996-01-11 Philips Electronics N.V. Circuit redresseur a pont ayant des commutateurs actifs et un circuit de commande actif

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3434034A (en) * 1967-03-14 1969-03-18 Hewlett Packard Co Universal ac or dc to dc converter
JPS63190561A (ja) * 1987-01-29 1988-08-08 Nec Corp 整流回路
US5268833A (en) * 1991-05-14 1993-12-07 U.S. Philips Corporation Rectifier circuit including FETs of the same conductivity type
WO1996001003A1 (fr) * 1994-06-29 1996-01-11 Philips Electronics N.V. Circuit redresseur a pont ayant des commutateurs actifs et un circuit de commande actif

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PATENT ABSTRACTS OF JAPAN 8 August 1988 (1988-08-08) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8804389B2 (en) 2012-02-16 2014-08-12 Linear Technology Corporation Active bridge rectification
US11286131B2 (en) 2015-03-24 2022-03-29 Kone Corporation Energizing circuit of a magnetizing coil of an operational brake, a passenger conveyor, and a method for energizing the magnetizing coil of the operational brake of a passenger conveyor

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