WO2016155818A1 - Unipolar inverter topology for simultaneous driving of brushless dc motors - Google Patents

Unipolar inverter topology for simultaneous driving of brushless dc motors Download PDF

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Publication number
WO2016155818A1
WO2016155818A1 PCT/EP2015/057217 EP2015057217W WO2016155818A1 WO 2016155818 A1 WO2016155818 A1 WO 2016155818A1 EP 2015057217 W EP2015057217 W EP 2015057217W WO 2016155818 A1 WO2016155818 A1 WO 2016155818A1
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WO
WIPO (PCT)
Prior art keywords
motor
brushless
converter circuit
freewheeling
electric motor
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PCT/EP2015/057217
Other languages
French (fr)
Inventor
Latif Tezduyar
Original Assignee
Arcelik Anonim Sirketi
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Priority to PCT/EP2015/057217 priority Critical patent/WO2016155818A1/en
Publication of WO2016155818A1 publication Critical patent/WO2016155818A1/en

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    • 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
    • H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
    • H02P5/68—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more dc dynamo-electric motors
    • H02P5/685—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more dc dynamo-electric motors electrically connected in series, i.e. carrying the same current
    • 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
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • H02P25/08—Reluctance motors
    • H02P25/092—Converters specially adapted for controlling reluctance motors
    • H02P25/0925—Converters specially adapted for controlling reluctance motors wherein the converter comprises only one switch per phase
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47L—DOMESTIC WASHING OR CLEANING; SUCTION CLEANERS IN GENERAL
    • A47L15/00—Washing or rinsing machines for crockery or tableware
    • A47L15/42—Details
    • A47L15/4214—Water supply, recirculation or discharge arrangements; Devices therefor
    • A47L15/4225—Arrangements or adaption of recirculation or discharge pumps
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47L—DOMESTIC WASHING OR CLEANING; SUCTION CLEANERS IN GENERAL
    • A47L15/00—Washing or rinsing machines for crockery or tableware
    • A47L15/42—Details
    • A47L15/46—Devices for the automatic control of the different phases of cleaning ; Controlling devices
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F39/00—Details of washing machines not specific to a single type of machines covered by groups D06F9/00 - D06F27/00 
    • D06F39/08—Liquid supply or discharge arrangements
    • D06F39/083—Liquid discharge or recirculation arrangements

Definitions

  • the present invention relates to a control circuit capable of simultaneously driving a pair of brushless dc motors.
  • Brushless direct current electric motors are synchronous motors comprising a rotor generally with permanent magnets and a stator with windings timing and direction of the current flow through different phases of which is controlled to ensure the operation of the motor.
  • mechanical switching parts i.e. brushes of the motor are replaced in the manner that an electronic control circuit typically accomplishes brushless DC motor control whereby the motor is electronically commutated during which the current is transferred from one phase to another.
  • Brushless DC electric motors are powered by a DC electric source via a switching power supply such as bipolar or unipolar driver circuits.
  • a switching power supply such as bipolar or unipolar driver circuits.
  • conduction occurs during the positive part of the back emf resulting in that a simpler switching circuit is used while a bipolar driver circuit requires an increased number of switching elements due to conduction occurring during positive and negative half-cycles.
  • a conventional driver circuit topology suitable for effecting bipolar current flow through each phase of the stator windings provides a costlier yet more efficient electronic control.
  • a bipolar driver circuit driving a three-phase brushless DC motor typically comprises six switching devices with integrated diodes, three of those requiring high-side switching gate drivers.
  • phase currents being not reversed in a unipolar driver circuit, a reduced number of switching devices will be necessary for the operation of the brushless DC motor.
  • a unipolar driver circuit also driving a three-phase (P1, P2 and P3) brushless DC motor, comprises three switching devices (S2, S4, and S6).
  • Each switching device is in series with a respective phase winding (P1, P2 and P3) and a respective Zener diode is provided in the freewheeling paths with diodes D2, D4 and D6, by which the stored magnetic energy in the respective phases is dissipated.
  • US5471353 discloses a disk drive system for use in limited power applications.
  • the disk drive includes a spindle motor having two or more windings, along with a spindle motor driver which can drive the spindle motor in any of a unipolar, bipolar or tripolar mode.
  • the bipolar or tripolar mode is used to start the disk drive and then the unipolar mode is used to operate the disk drive while data is being retrieved.
  • By combining the three drive modes a large start current reduction and high rotation velocities are achieved. Current consumption is minimized by transitioning from bipolar to unipolar modes.
  • the present invention addresses the situation where a plurality of semi-conductor devices are used in a circuit topology simultaneously driving a pair of brushless DC motors.
  • the present invention provides an effective circuit solution by which the least number of semi-conductor switching devices are needed for simultaneously driving a pair of brushless DC motors in an electrical household appliance. Therefore, the present invention is devised under the recognition that a more cost-efficient circuit topology for simultaneously driving two brushless DC motors remains a need.
  • the present invention provides an inverter circuit, as provided by the characterizing features defined in Claim 1.
  • Primary object of the present invention is to provide an inverter circuit capable of simultaneously driving a pair of brushless dc motors in an electrical household appliance.
  • the present invention proposes a converter circuit for optionally simultaneously driving a first brushless DC electric motor and a second brushless DC electric motor of an electrical household appliance.
  • First and second motor unipolar inverters sequentially energize phase windings of the first and second motors.
  • the second motor phase windings in series with the second motor switching devices are disposed across positive and negative supply lines and freewheeling diodes in association with a respective second motor switching device conveys current flow to a freewheeling line during the off-time of the respective switching device.
  • the converter circuit includes a commutation energy control circuit with a freewheeling line switching device across a freewheeling line and the positive supply line so that either current flow to a storage capacitor across the freewheeling line and the negative supply line is interrupted and the commutation energy control circuit selectively drives the first brushless DC electric motor during simultaneous operation of the first and second motors or the stored magnetic field energy in the second motor phase windings is transferred to the storage capacitor.
  • the positive supply line is connected to first motor inverter diodes so that the freewheeling line switching device can supply current to the positive supply line when in conduction mode.
  • Fig. 1 demonstrates a schematic of an inverter for a three-phase unipolar brushless DC motor.
  • Fig. 2 demonstrates a schematic of a circuit topology for simultaneously driving two brushless DC motors according to the present invention.
  • Fig. 3 demonstrates a schematic of a circuit topology for simultaneously driving two brushless DC motors according to an alternative embodiment of the present invention.
  • the present invention proposes a circuit topology for simultaneously driving a pair of brushless DC motors in an electrical household appliance such as dishwasher or laundry machine comprising a first electric motor responsible for circulating processing water and a second electric motor effecting water discharge.
  • stator windings inductive elements
  • stator windings are switched on and off depending on the rotor position.
  • the magnetic fields of the stator and rotor i.e. the rotating magnetic field created by timely changing the direction of the current flow through different phases of the stator windings with respect to the rotor’s magnetic field are synchronized.
  • a first motor unipolar inverter (1) controls the energy flow to the discharge pump motor windings and a second motor unipolar inverter (2) drives the circulation pump motor as will be delineated hereinafter.
  • a unipolar inverter typically limits the windings to a single direction of current to energize the same and the energy stored in a respective winding is dissipated in the same winding through reverse-parallel diodes, thereby proving to be an economic but inefficient power conversion. It is yet to be noted that cost advantage is a critical issue as the inverter for the motor is more expansive than the motor itself.
  • the circulation motor (SP) is preferably a three-phase motor with second motor switching devices 10 (S1, S2 and S3), being typically IGBT, FET or MOSFET. Each switching device 10 energizes a respective second motor phase winding 4 (SP P1, SP P2, and SP P3).
  • the discharge motor (TP) is a two-phase motor having two first motor switching devices 9 (S5 and S6), each one sequentially energizing a respective first motor phase winding 3 (TP P1 and TP P2).
  • an alternating voltage source is rectified by four rectifier diodes 5 (D5, D6, D7 and D8) while first motor inverter diodes 6 (D5 and D6) are connected in series with the first motor phase windings 3 (TP P1 and TP P2).
  • the AC source voltage is rectified through rectifier diodes 5 (D7 and D8) while the first motor switching devices 9 (S5 and S6) energizes in timed sequence the associated first motor phase windings (3).
  • a respective first motor phase winding (3) is then deenergized through a respective first motor inverter diode (6) in series therewith.
  • Fig. 2 demonstrates a schematic of a circuit topology with positive and negative supply lines (13, 14) forming common connection points for the second motor phase windings (4) that are in series with second motor switching devices (10).
  • the second motor switching devices 10 While current flows through the second motor phase windings (4) depending on the rotor position, the second motor switching devices 10 (S1, S2 and S3) are turned on in timed sequence and the respective second motor phase winding (4) is energized.
  • a respective second motor switching device 10 S1, S2 and S3 is opened, an associated freewheeling diode 7 (D1, D2 and D3) allows current flow to a freewheeling line (15) so that excess energy is used to charge a storage capacitor (12).
  • a commutation energy control circuit (11) including a freewheeling line switching device 17 (S4) in series with a diode D4, when turned on, selectively interrupts current flow to the storage capacitor (12), thereby supplying current to the DC bus, i.e. the positive supply line (13).
  • a DC bus capacitor (17) is disposed across the positive and negative supply lines (13, 14) to smooth voltage ripple.
  • Fig. 3 demonstrates a second alternative embodiment according to the invention. Additionally an optional common freewheeling diode (8) is used in the circuits.
  • a conventional PWM scheme can be implemented to produce the desired Torque-Speed characteristics.
  • the amplitude of the applied voltage is adjusted by controlling the duty cycle of PWM pulses in accordance with the voltage amplitude to keep the desired speed.
  • the commutation energy control circuit (11) provides that excess energy of the second motor phase windings (4) generating a freewheeling current returning from the second motor unipolar inverter (2) through the freewheeling line (15) is used to drive the discharge pump (TP) during simultaneous operation of the first and second motors. Therefore, the invention provides that stored magnetic field energy in the second motor phase windings 4 (SP P1, SP P2, and SP P3) is either transferred to the storage capacitor 12 or used to drive the discharge pump (TP).
  • the freewheeling path established through the reverse-parallel diodes also provides a more efficient high-speed operation for the circulation motor (SP) as the commutation energy control circuit (11) produces the effect of boosting the DC bus (16) voltage, which in turn minimizes harmonics drawn from the mains as it functions as an active PFC.
  • SP circulation motor
  • the commutation energy control circuit (11) produces the effect of boosting the DC bus (16) voltage, which in turn minimizes harmonics drawn from the mains as it functions as an active PFC.
  • the present invention proposes a converter circuit for driving a first brushless DC electric motor and a second brushless DC electric motor of an electrical household appliance, the converter circuit comprising a first motor unipolar inverter (1) controlling energy flow to the first brushless DC electric motor by means of first motor switching devices (9) energizing a respective first motor phase winding (3) in timed sequence and a second motor unipolar inverter (2) controlling energy flow to the second brushless DC electric motor by means of second motor switching devices (10) energizing a respective second motor phase winding (4) in timed sequence, the converter circuit having positive and negative supply lines (13, 14) forming common connection points for the second motor phase windings (4) that are in series with the second motor switching devices (10) and freewheeling diodes (7) in association with a respective second motor switching device (10) effecting current flow to a freewheeling line (15) when the latter switching device is opened.
  • first motor unipolar inverter (1) controlling energy flow to the first brushless DC electric motor by means of first motor switching devices (9)
  • the converter circuit comprises a commutation energy control circuit (11) functional in that a freewheeling line switching device (17) across the freewheeling line (15) and the positive supply line (13) selectively interrupts current flow to a storage capacitor (12) across the freewheeling line (15) and the negative supply line (14).
  • the commutation energy control circuit (11) selectively drives the first brushless DC electric motor during simultaneous operation of the first and second motors.
  • the stored magnetic field energy in the second motor phase windings (4) is either transferred to the storage capacitor (12) or used to drive the first brushless DC electric motor.
  • the freewheeling line switching device (17) supplies current to the positive supply line (13) when in conduction mode.
  • the positive supply line (13) is connected to first motor inverter diodes (6) being in parallel with each other.
  • the freewheeling line switching device (17) is in series with a forward-biased diode (D4).
  • a DC bus capacitor (17) is disposed across the positive and negative supply lines (13, 14).
  • an AC source voltage is rectified through rectifier diodes (5) while the first motor switching devices (9) energizes in timed sequence the associated first motor phase windings (3).
  • the first brushless DC electric motor is a two-phase motor.
  • the second brushless DC electric motor is a three-phase motor.
  • an electrical household appliance comprising a converter circuit is proposed.
  • the appliance is a laundry machine in the form of a washing, drying or washing and drying machine or a dishwasher.
  • the present invention provides that a first brushless DC motor as a two-phase discharge pump motor and a second brushless DC motor as a three-phase circulation pump motor can be simultaneously driven without using two bipolar inverters having ten switching devices, half of which requiring high-side switching gate drivers.
  • circuit topology according to the present invention affords a much cost-effective circuit solution which involves five switching devices, only one of those requiring a high-side switching gate driver.
  • other side benefits include use of a smaller or single-sided PCB as well as the possibility for a more compact heat sink.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

The present invention relates to a converter circuit for driving a first brushless DC electric motor and a second brushless DC electric motor of an electrical household appliance, the converter circuit comprising a first motor unipolar inverter (1) controlling energy flow to the first brushless DC electric motor by means of first motor switching devices (9) energizing a respective first motor phase winding (3) in timed sequence and a second motor unipolar inverter (2) controlling energy flow to the second brushless DC electric motor by means of second motor switching devices (10) energizing a respective second motor phase winding (4) in timed sequence, the converter circuit having positive and negative supply lines (13, 14) forming common connection points for the second motor phase windings (4) that are in series with the second motor switching devices (10) and freewheeling diodes (7) in association with a respective second motor switching device (10) effecting current flow to a freewheeling line (15) when the latter switching device is opened.

Description

UNIPOLAR INVERTER TOPOLOGY FOR SIMULTANEOUS DRIVING OF BRUSHLESS DC MOTORS
The present invention relates to a control circuit capable of simultaneously driving a pair of brushless dc motors.
It is well-known that household appliances such as for instance dishwashers or washing machines are equipped with a plurality of electrical motors effectuating the operations of circulation of the washing water and water discharge. Small power brushless DC (BLDC) motors typically in the range of 100-120 W are preferred in these applications as limited torque motors in view of their compact size, high efficiency and silent operation.
Brushless direct current electric motors are synchronous motors comprising a rotor generally with permanent magnets and a stator with windings timing and direction of the current flow through different phases of which is controlled to ensure the operation of the motor. In brushless DC motors, mechanical switching parts, i.e. brushes of the motor are replaced in the manner that an electronic control circuit typically accomplishes brushless DC motor control whereby the motor is electronically commutated during which the current is transferred from one phase to another.
Brushless DC electric motors are powered by a DC electric source via a switching power supply such as bipolar or unipolar driver circuits. In a unipolar driver circuit, conduction occurs during the positive part of the back emf resulting in that a simpler switching circuit is used while a bipolar driver circuit requires an increased number of switching elements due to conduction occurring during positive and negative half-cycles.
A conventional driver circuit topology suitable for effecting bipolar current flow through each phase of the stator windings provides a costlier yet more efficient electronic control. A bipolar driver circuit driving a three-phase brushless DC motor typically comprises six switching devices with integrated diodes, three of those requiring high-side switching gate drivers. On the other hand, phase currents being not reversed in a unipolar driver circuit, a reduced number of switching devices will be necessary for the operation of the brushless DC motor.
Referring to Fig. 1, a unipolar driver circuit, also driving a three-phase (P1, P2 and P3) brushless DC motor, comprises three switching devices (S2, S4, and S6). Each switching device is in series with a respective phase winding (P1, P2 and P3) and a respective Zener diode is provided in the freewheeling paths with diodes D2, D4 and D6, by which the stored magnetic energy in the respective phases is dissipated.
Among others, a prior art publication Vin the technical field of the invention may be referred to as US5471353, which discloses a disk drive system for use in limited power applications. The disk drive includes a spindle motor having two or more windings, along with a spindle motor driver which can drive the spindle motor in any of a unipolar, bipolar or tripolar mode. The bipolar or tripolar mode is used to start the disk drive and then the unipolar mode is used to operate the disk drive while data is being retrieved. By combining the three drive modes a large start current reduction and high rotation velocities are achieved. Current consumption is minimized by transitioning from bipolar to unipolar modes.
The present invention, on the other hand, addresses the situation where a plurality of semi-conductor devices are used in a circuit topology simultaneously driving a pair of brushless DC motors. As cost minimization is critical to the large volume manufacture, the present invention provides an effective circuit solution by which the least number of semi-conductor switching devices are needed for simultaneously driving a pair of brushless DC motors in an electrical household appliance. Therefore, the present invention is devised under the recognition that a more cost-efficient circuit topology for simultaneously driving two brushless DC motors remains a need.
The present invention provides an inverter circuit, as provided by the characterizing features defined in Claim 1.
Primary object of the present invention is to provide an inverter circuit capable of simultaneously driving a pair of brushless dc motors in an electrical household appliance.
The present invention proposes a converter circuit for optionally simultaneously driving a first brushless DC electric motor and a second brushless DC electric motor of an electrical household appliance. First and second motor unipolar inverters sequentially energize phase windings of the first and second motors.
The second motor phase windings in series with the second motor switching devices are disposed across positive and negative supply lines and freewheeling diodes in association with a respective second motor switching device conveys current flow to a freewheeling line during the off-time of the respective switching device.
The converter circuit includes a commutation energy control circuit with a freewheeling line switching device across a freewheeling line and the positive supply line so that either current flow to a storage capacitor across the freewheeling line and the negative supply line is interrupted and the commutation energy control circuit selectively drives the first brushless DC electric motor during simultaneous operation of the first and second motors or the stored magnetic field energy in the second motor phase windings is transferred to the storage capacitor.
The positive supply line is connected to first motor inverter diodes so that the freewheeling line switching device can supply current to the positive supply line when in conduction mode.
Accompanying drawings are given solely for the purpose of exemplifying a control circuit capable of simultaneously driving a pair of brushless dc motors, whose advantages over prior art were outlined above and will be explained in brief hereinafter.
The drawings are not meant to delimit the scope of protection as identified in the Claims, nor should they be referred to alone in an effort to interpret the scope identified in the Claims without recourse to the technical disclosure in the description of the present invention.
Fig. 1 demonstrates a schematic of an inverter for a three-phase unipolar brushless DC motor.
Fig. 2 demonstrates a schematic of a circuit topology for simultaneously driving two brushless DC motors according to the present invention.
Fig. 3 demonstrates a schematic of a circuit topology for simultaneously driving two brushless DC motors according to an alternative embodiment of the present invention.
The following numerals are assigned to different part number used in the detailed description:
  1. First motor unipolar inverter
  2. Second motor unipolar inverter
  3. First motor phase winding
  4. Second motor phase winding
  5. Rectifier diodes
  6. First motor inverter diode
  7. Freewheeling diode
  8. Common freewheeling diode
  9. First motor switching device
  10. Second motor switching device
  11. Commutation energy control circuit
  12. Storage capacitor
  13. Positive supply line
  14. Negative supply line
  15. Freewheeling line
  16. Freewheeling line switching device
  17. DC bus capacitor
The present invention proposes a circuit topology for simultaneously driving a pair of brushless DC motors in an electrical household appliance such as dishwasher or laundry machine comprising a first electric motor responsible for circulating processing water and a second electric motor effecting water discharge.
In a brushless DC motor, the stator windings (inductive elements) are switched on and off depending on the rotor position. The magnetic fields of the stator and rotor, i.e. the rotating magnetic field created by timely changing the direction of the current flow through different phases of the stator windings with respect to the rotor’s magnetic field are synchronized.
According to the present invention, a first motor unipolar inverter (1) controls the energy flow to the discharge pump motor windings and a second motor unipolar inverter (2) drives the circulation pump motor as will be delineated hereinafter. In contrast to a bipolar inverter which allows bipolar current flow through stator phase windings in a brushless DC motor, a unipolar inverter typically limits the windings to a single direction of current to energize the same and the energy stored in a respective winding is dissipated in the same winding through reverse-parallel diodes, thereby proving to be an economic but inefficient power conversion. It is yet to be noted that cost advantage is a critical issue as the inverter for the motor is more expansive than the motor itself.
According to the present invention, the circulation motor (SP) is preferably a three-phase motor with second motor switching devices 10 (S1, S2 and S3), being typically IGBT, FET or MOSFET. Each switching device 10 energizes a respective second motor phase winding 4 (SP P1, SP P2, and SP P3). On the other hand, the discharge motor (TP) is a two-phase motor having two first motor switching devices 9 (S5 and S6), each one sequentially energizing a respective first motor phase winding 3 (TP P1 and TP P2).
According to the present invention, an alternating voltage source is rectified by four rectifier diodes 5 (D5, D6, D7 and D8) while first motor inverter diodes 6 (D5 and D6) are connected in series with the first motor phase windings 3 (TP P1 and TP P2). The AC source voltage is rectified through rectifier diodes 5 (D7 and D8) while the first motor switching devices 9 (S5 and S6) energizes in timed sequence the associated first motor phase windings (3). A respective first motor phase winding (3) is then deenergized through a respective first motor inverter diode (6) in series therewith. Fig. 2 demonstrates a schematic of a circuit topology with positive and negative supply lines (13, 14) forming common connection points for the second motor phase windings (4) that are in series with second motor switching devices (10).
According to a first embodiment of the present invention, while current flows through the second motor phase windings (4) depending on the rotor position, the second motor switching devices 10 (S1, S2 and S3) are turned on in timed sequence and the respective second motor phase winding (4) is energized. When a respective second motor switching device 10 (S1, S2 and S3) is opened, an associated freewheeling diode 7 (D1, D2 and D3) allows current flow to a freewheeling line (15) so that excess energy is used to charge a storage capacitor (12).
On the other hand, a commutation energy control circuit (11) including a freewheeling line switching device 17 (S4) in series with a diode D4, when turned on, selectively interrupts current flow to the storage capacitor (12), thereby supplying current to the DC bus, i.e. the positive supply line (13). Optionally, a DC bus capacitor (17) is disposed across the positive and negative supply lines (13, 14) to smooth voltage ripple. Fig. 3 demonstrates a second alternative embodiment according to the invention. Additionally an optional common freewheeling diode (8) is used in the circuits.
A conventional PWM scheme can be implemented to produce the desired Torque-Speed characteristics. The amplitude of the applied voltage is adjusted by controlling the duty cycle of PWM pulses in accordance with the voltage amplitude to keep the desired speed.
The commutation energy control circuit (11) provides that excess energy of the second motor phase windings (4) generating a freewheeling current returning from the second motor unipolar inverter (2) through the freewheeling line (15) is used to drive the discharge pump (TP) during simultaneous operation of the first and second motors. Therefore, the invention provides that stored magnetic field energy in the second motor phase windings 4 (SP P1, SP P2, and SP P3) is either transferred to the storage capacitor 12 or used to drive the discharge pump (TP).
When needed, the freewheeling path established through the reverse-parallel diodes also provides a more efficient high-speed operation for the circulation motor (SP) as the commutation energy control circuit (11) produces the effect of boosting the DC bus (16) voltage, which in turn minimizes harmonics drawn from the mains as it functions as an active PFC.
In a nutshell, the present invention proposes a converter circuit for driving a first brushless DC electric motor and a second brushless DC electric motor of an electrical household appliance, the converter circuit comprising a first motor unipolar inverter (1) controlling energy flow to the first brushless DC electric motor by means of first motor switching devices (9) energizing a respective first motor phase winding (3) in timed sequence and a second motor unipolar inverter (2) controlling energy flow to the second brushless DC electric motor by means of second motor switching devices (10) energizing a respective second motor phase winding (4) in timed sequence, the converter circuit having positive and negative supply lines (13, 14) forming common connection points for the second motor phase windings (4) that are in series with the second motor switching devices (10) and freewheeling diodes (7) in association with a respective second motor switching device (10) effecting current flow to a freewheeling line (15) when the latter switching device is opened.
In one embodiment of the present invention, the converter circuit comprises a commutation energy control circuit (11) functional in that a freewheeling line switching device (17) across the freewheeling line (15) and the positive supply line (13) selectively interrupts current flow to a storage capacitor (12) across the freewheeling line (15) and the negative supply line (14).
In a further embodiment of the present invention, the commutation energy control circuit (11) selectively drives the first brushless DC electric motor during simultaneous operation of the first and second motors.
In a further embodiment of the present invention, the stored magnetic field energy in the second motor phase windings (4) is either transferred to the storage capacitor (12) or used to drive the first brushless DC electric motor.
In a further embodiment of the present invention, the freewheeling line switching device (17) supplies current to the positive supply line (13) when in conduction mode.
In a further embodiment of the present invention, the positive supply line (13) is connected to first motor inverter diodes (6) being in parallel with each other.
In a further embodiment of the present invention, the freewheeling line switching device (17) is in series with a forward-biased diode (D4).
In a further embodiment of the present invention, a DC bus capacitor (17) is disposed across the positive and negative supply lines (13, 14).
In a further embodiment of the present invention, an AC source voltage is rectified through rectifier diodes (5) while the first motor switching devices (9) energizes in timed sequence the associated first motor phase windings (3).
In a further embodiment of the present invention, the first brushless DC electric motor is a two-phase motor.
In a further embodiment of the present invention, the second brushless DC electric motor is a three-phase motor.
In a further embodiment of the present invention, an electrical household appliance comprising a converter circuit is proposed.
In a further embodiment of the present invention, the appliance is a laundry machine in the form of a washing, drying or washing and drying machine or a dishwasher.
Therefore, the present invention provides that a first brushless DC motor as a two-phase discharge pump motor and a second brushless DC motor as a three-phase circulation pump motor can be simultaneously driven without using two bipolar inverters having ten switching devices, half of which requiring high-side switching gate drivers.
The circuit topology according to the present invention affords a much cost-effective circuit solution which involves five switching devices, only one of those requiring a high-side switching gate driver. Apart from economic advantages, other side benefits include use of a smaller or single-sided PCB as well as the possibility for a more compact heat sink.

Claims (12)

  1. A converter circuit for driving a first brushless DC electric motor and a second brushless DC electric motor of an electrical household appliance, the converter circuit comprising a first motor unipolar inverter (1) controlling energy flow to the first brushless DC electric motor by means of first motor switching devices (9) energizing a respective first motor phase winding (3) in timed sequence and a second motor unipolar inverter (2) controlling energy flow to the second brushless DC electric motor by means of second motor switching devices (10) energizing a respective second motor phase winding (4) in timed sequence, the converter circuit having positive and negative supply lines (13, 14) forming common connection points for the second motor phase windings (4) that are in series with the second motor switching devices (10) and freewheeling diodes (7) in association with a respective second motor switching device (10) effecting current flow to a freewheeling line (15) when the latter switching device is opened, characterized in that
    the converter circuit comprises a commutation energy control circuit (11) functional in that a freewheeling line switching device (17) across the freewheeling line (15) and the positive supply line (13) selectively interrupts current flow to a storage capacitor (12) across the freewheeling line (15) and the negative supply line (14).
  2. A converter circuit as in Claim 1, characterized in that the commutation energy control circuit (11) selectively drives the first brushless DC electric motor during simultaneous operation of the first and second motors.
  3. A converter circuit as in Claim 1 or 2, characterized in that the stored magnetic field energy in the second motor phase windings (4) is either transferred to the storage capacitor (12) or used to drive the first brushless DC electric motor.
  4. A converter circuit as in Claim 3, characterized in that the freewheeling line switching device (17) supplies current to the positive supply line (13) when in conduction mode.
  5. A converter circuit as in Claim 4, characterized in that the positive supply line (13) is connected to first motor inverter diodes (6) being in parallel with each other.
  6. A converter circuit as in Claim 4 or 5, characterized in that the freewheeling line switching device (17) is in series with a forward-biased diode (D4).
  7. A converter circuit as in Claim 6, characterized in that a DC bus capacitor (17) is disposed across the positive and negative supply lines (13, 14).
  8. A converter circuit as in Claim 5, characterized in that an AC source voltage is rectified through rectifier diodes (5) while the first motor switching devices (9) energizes in timed sequence the associated first motor phase windings (3).
  9. A converter circuit as in Claim 1, characterized in that the first brushless DC electric motor is a two-phase motor.
  10. A converter circuit as in Claim 1, characterized in that the second brushless DC electric motor is a three-phase motor.
  11. An electrical household appliance comprising the converter circuit of Claim 1.
  12. An electrical household appliance as in Claim 11, wherein the appliance is a laundry washing/drying machine or a dishwasher.
PCT/EP2015/057217 2015-04-01 2015-04-01 Unipolar inverter topology for simultaneous driving of brushless dc motors WO2016155818A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3656953A1 (en) * 2018-11-21 2020-05-27 Meteor S.a.s. di Fabio Dell'Oglio & C. Actuator with improved safety

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US5471353A (en) 1992-12-18 1995-11-28 Western Digital (Sea), Pte., Ltd. Disk drive employing multi-mode spindle drive system
EP0802623A1 (en) * 1996-04-19 1997-10-22 Switched Reluctance Drives Limited Converter circuit for a polyphase switched inductive load
US5703456A (en) * 1995-05-26 1997-12-30 Emerson Electric Co. Power converter and control system for a motor using an inductive load and method of doing the same
WO2000029660A1 (en) * 1998-11-17 2000-05-25 Fisher & Paykel Limited Laundry machine
EP2428608A1 (en) * 2010-09-14 2012-03-14 Miele & Cie. KG Method for operating a pump in a water-bearing device, mechatronic system and washing machine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5471353A (en) 1992-12-18 1995-11-28 Western Digital (Sea), Pte., Ltd. Disk drive employing multi-mode spindle drive system
US5703456A (en) * 1995-05-26 1997-12-30 Emerson Electric Co. Power converter and control system for a motor using an inductive load and method of doing the same
EP0802623A1 (en) * 1996-04-19 1997-10-22 Switched Reluctance Drives Limited Converter circuit for a polyphase switched inductive load
WO2000029660A1 (en) * 1998-11-17 2000-05-25 Fisher & Paykel Limited Laundry machine
EP2428608A1 (en) * 2010-09-14 2012-03-14 Miele & Cie. KG Method for operating a pump in a water-bearing device, mechatronic system and washing machine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3656953A1 (en) * 2018-11-21 2020-05-27 Meteor S.a.s. di Fabio Dell'Oglio & C. Actuator with improved safety

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