Washing machine for washing articles equipped with an electric drive unit to operate electric motors
A washing machine having a first single phase electric motor, a second single phase electric motor and an electric drive unit for the electric motors. The electric drive unit is connected to power supply lines and comprises three first legs, each leg comprising a pair of switches. Electrical terminals of the first electric motor are connected to the first and second legs of the electric drive unit and electrical terminals of the second electric motor are connected to the second and third legs of the electric drive unit.
1. A washing machine having a first single phase electric motor, a second single phase electric motor and an electric drive unit configured to operate the electric motors, the electric drive unit being connected to a first power supply line and a second power supply line, wherein the electric drive unit comprises:
a first leg comprising a first switch and a second switch connected in series between the first power supply line and the second power supply line;
a second leg comprising a third switch and a fourth switch connected in series between the first power supply line and the second power supply line;
a third leg comprising a fifth switch and a sixth switch connected in series between the first power supply line and the second power supply line;
wherein a first electrical terminal of the first electric motor is connected to the first leg and a second electrical terminal of the first electric motor is connected to the second leg and wherein a first electrical terminal of the second electric motor is connected to the second leg and a second electrical terminal of the second electric motor is connected to the third leg.
2. The washing machine according to claim 1 , wherein the first electrical terminal of the first electric motor is connected to a node between the first switch and the second switch of the first leg and the second electrical terminal of the first electric motor is connected to a node between the third switch and the fourth switch of the second leg and wherein the first electrical terminal of the second electric motor is connected to a node between the third switch and the fourth switch of the second leg and the second electrical terminal of the second electric motor is connected to a node between the fifth switch and the sixth switch of the third leg.
3. The washing machine according to claim 1 , wherein the switches comprise solid-state switches.
4. The washing machine according to claim 3 , wherein one or more of the switches comprises a free-wheel diode.
5. The washing machine according to claim 3 , wherein the switches comprise MOSFETs or IGBTs.
6. The washing machine according to claim 1 , wherein the first leg comprises a first resistor, wherein the first resistor is connected between the second switch and the second power supply line.
7. The washing machine according to claim 6 , wherein the second leg comprises a second resistor, wherein the second resistor is connected between the fourth switch and the second power supply line.
8. The washing machine according to claim 7 , wherein the third leg comprises a third resistor, wherein the third resistor is connected between the sixth switch and the second power supply line.
9. The washing machine according to claim 1 , further comprising a control unit configured to operate each one of the switches.
10. The washing machine according to claim 9 , wherein the control unit is configured to operate the first to fourth switches to activate the first electric motor.
11. The washing machine according to claim 10 , wherein the control unit is configured to operate the first to fourth switches according to a PWM technique.
12. The washing machine according to claim 10 , wherein the control unit is configured to operate the third to sixth switches to activate the second electric motor.
13. The washing machine according to claim 12 , wherein the control unit is configured to operate the third to sixth switches according to a PWM technique.
14. The washing machine according to claim 1 , wherein at least one of the first electric motor and the second electric motor comprises a synchronous electric motor.
15. The washing machine according to claim 1 , wherein at least one of the first electric motor and the second electric motor is comprises an electric motor operatively connected to a pump provided in the washing machine.
16. The washing machine according to claim 1 , wherein the first power supply line and the second power supply line are connected to a AC voltage system via a rectifier unit and a DC voltage intermediate circuit.