DC to DC converter sourcing variable DC link voltage
An inverter-converter system includes a DC source, a DC to DC boost converter, a DC link capacitor, an inverter circuit, a variable speed electric machine, and a controller. The DC to DC boost converter receives an input DC voltage from the DC source. The inverter circuit converts the variable boosted voltage to an AC voltage to drive the variable speed electric machine. The controller senses a plurality of parameters from the variable speed electric machine, and controls the DC to DC boost converter to boost up the input DC voltage to a variable output voltage based on the plurality of parameters and/or the voltage (or load) needed by the variable speed electric machine. The design of the inverter-converter system can achieve an electrical efficiency and cost savings for the overall system.
1. A boost converter, comprising:
a first boost circuit having a first switch configured to be connected to a first coil, the first coil having a first end and a second end; and
a second boost circuit having a second switch configured to be connected to a second coil, the second coil having a first end and a second end,
wherein the first boost circuit is configured to be connected to a power source to receive an input voltage from the power source and the first boost circuit connects to the second boost circuit;
wherein the first switch is controlled to boost the input voltage received from the power source to a first boosted voltage using the first coil without the second coil;
wherein the second switch is controlled to boost the input voltage received from the power source to a second boosted voltage using the first coil and the second coil;
wherein the second boosted voltage is greater than the first boosted voltage, the first boosted voltage is greater than the input voltage received from the power source;
wherein the first coil is configured to be connected to the second coil in series when the second switch is controlled to boost the input voltage received from the power source to the second boosted voltage;
wherein the boost converter is configured to provide the first boosted voltage to operate a load at a first operational level, and the boost converter is configured to provide the second boosted voltage to operate the load at a second operational level that is different from the first operational level; and
wherein the boost converter is configured to provide the first boosted voltage to operate a compressor at a first speed, and the boost converter is configured to provide the second boosted voltage to operate the compressor at a second speed that is greater than the first speed.
2. The boost converter according to claim 1 , wherein the first switch and the second switch are MOSFET switches.
3. The boost converter according to claim 2 , further comprising:
a capacitor,
wherein the capacitor connects to the first boost circuit and the second boost circuit;
wherein a terminal of the second switch is configured to be connected to the second end of the second coil; and
wherein the second end of the first coil and a terminal of the first switch are configured to be connected to the first end of the second coil.
4. The boost converter according to claim 1 , further comprising:
a third boost circuit having a third switch configured to be connected to a third coil,
wherein the first boost circuit is configured to boost the input voltage received from the power source to the first boosted voltage;
wherein the first coil and the second boost circuit are configured to boost the input voltage received from the power source to the second boosted voltage;
wherein the first coil, the second coil, and the third boost circuit are configured to boost the input voltage received from the power source to a third boosted voltage; and
wherein the first coil, the second coil, and the third coil are configured to be connected in series when the third switch is controlled to boost the input voltage received from the power source to the third boosted voltage.
5. The boost converter according to claim 1 , wherein the boost converter is configured to be connected to the compressor via an inverter.
6. An inverter-converter system, comprising:
a boost converter, the boost converter includes:
a first boost circuit having a first switch configured to be connected to a first coil, the first coil having a first end and a second end, and
a second boost circuit having a second switch configured to be connected to a second coil, the second coil having a first end and a second end,
wherein the first boost circuit is configured to be connected to a power source to receive an input voltage from the power source and the first boost circuit connects to the second boost circuit,
wherein the first switch is controlled to boost the input voltage received from the power source to a first boosted voltage using the first coil without the second coil,
wherein the second switch is controlled to boost the input voltage received from the power source to a second boosted voltage using the first coil and the second coil;
wherein the first coil is configured to be connected to the second coil in series when the second switch is controlled to boost the input voltage received from the power source to the second boosted voltage; and
wherein the second boosted voltage is greater than the first boosted voltage, the first boosted voltage is greater than the input voltage received from the power source;
the power source providing the input voltage received from the power source to the boost converter;
a variable speed electric machine; and
a controller that determines a load of the variable speed electric machine and controls the first and the second switch based on the sensed load of the variable speed electric machine,
wherein the boost converter is configured to source one of the first boosted voltage and the second boosted voltage to the variable speed electric machine based on the sensed load of the variable speed electric machine,
the boost converter is configured to provide the first boosted voltage to operate the variable speed electric machine at a first operational level, and the boost converter is configured to provide the second boosted voltage to operate the variable speed electric machine at a second operational level that is different from the first operational level, and
the variable speed electric machine is a compressor, the boost converter is configured to provide the first boosted voltage to operate the compressor at a first speed, and the boost converter is configured to provide the second boosted voltage to operate the compressor at a second speed that is greater than the first speed.
7. The inverter-converter system according to claim 6 , further comprising:
an inverter circuit for converting one of the first boosted voltage and the second boosted voltage to an AC voltage,
wherein the variable speed electric machine is driven by the AC voltage.
8. The inverter-converter system according to claim 6 , wherein the input voltage received from the power source is about 12 volts.
9. The inverter-converter system according to claim 6 , wherein the power source is one of a battery source, a DC source, and an AC source.
10. The inverter-converter system according to claim 6 , wherein the first boosted voltage is about 170 volts and the second boosted voltage is about 340 volts.
11. The inverter-converter system according to claim 6 , wherein the variable speed electric machine is a multi-speed AC-driven compressor.
12. The inverter-converter system according to claim 6 , wherein the boost converter is configured to be connected to the compressor via an inverter.
13. A method for operating a boost converter, the boost converter including a first boost circuit having a first switch configured to be connected to a first coil, the first coil having a first end and a second end; and a second boost circuit having a second switch configured to be connected to a second coil, the second coil having a first end and a second end, wherein the first boost circuit is configured to be connected to a power source to receive an input voltage from the power source and the first boost circuit connects to the second boost circuit,
the method comprising:
receiving the input voltage from the power source;
sensing a load of a variable speed electric machine;
when the load of the variable speed electric machine is sensed to require a first boosted voltage, controlling the first switch to boost the input voltage received from the power source to the first boosted voltage using the first coil without the second coil; and
when the load of the variable speed electric machine is sensed to require a second boosted voltage, controlling the second switch to boost the input voltage received from the power source to the second boosted voltage using the first coil and the second coil,
wherein the first coil is configured to be connected to the second coil in series when the second switch is controlled to boost the input voltage received from the power source to the second boosted voltage,
wherein the second boosted voltage is greater than the first boosted voltage, the first boosted voltage is greater than the input voltage received from the power source,
the method further comprising:
the boost converter providing the first boosted voltage to operate the variable speed electric machine at a first operational level; and the boost converter providing the second boosted voltage to operate the variable speed electric machine at a second operational level that is different from the first operational level, and
the boost converter providing the first boosted voltage to operate a compressor at a first speed; and the boost converter providing the second boosted voltage to operate the compressor at a second speed that is greater than the first speed.
14. The method according to claim 13 , wherein the boost converter further includes a third boost circuit having a third switch configured to be connected to a third coil,
the method further comprising:
when the load of the variable speed electric machine is sensed to require the first boosted voltage, the first boost circuit boosting the input voltage received from the power source to the first boosted voltage;
when the load of the variable speed electric machine is sensed to require the second boosted voltage, the first coil combined with the second boost circuit boosting the input voltage received from the power source to the second boosted voltage; and
when the load of the variable speed electric machine is sensed to require a third boosted voltage, the first coil and the second coil combined with the third boost circuit boosting the input voltage received from the power source to the third boosted voltage,
wherein the first coil, the second coil, and the third coil are configured to be connected in series when the third switch is controlled to boost the input voltage received from the power source to the third boosted voltage.
15. The method according to claim 13 , wherein the boost converter is configured to be connected to the compressor via an inverter.