AC CONVERSION CIRCUIT
First Claim
1. An AC converter that converts a single-phase input AC voltage with a frequency f0 into a three-phase output AC voltage with a frequency f1 that is lower than f0, the converter comprising:
- a switching section that converts the input AC voltage in response to a control signal and that outputs the converted voltage to a phase that has been selected in accordance with the control signal;
a filter section that filters out high frequency components from the converted voltage, thereby converting the converted voltage into the output AC voltage; and
a switching control section that performs a pulse density modulation on a phase-by-phase basis and based on a reference signal with the frequency f1 which is associated with the output AC voltage of each said phase, synchronously with a zero cross of the input AC voltage, thereby generating the control signal according to a pulse generation status by the pulse density modulation and the polarity of the input AC voltage and sending out the control signal to the switching section, andwherein the switching section includes a first type of switching element that applies a positive voltage to its associated phase if the polarity of the input AC voltage is positive and a second type of switching element that applies a positive voltage to its associated phase if the polarity of the input AC voltage is negative, andwherein if the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are both positive, the switching control section outputs the control signal to control the switching section to turn the first type of switching element ON, andif the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are negative and positive, respectively, the switching control section outputs the control signal to control the switching section to turn the second type of switching element ON, andif the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are positive and negative, respectively, the switching control section outputs the control signal to control the switching section to turn the second type of switching element ON, andif the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are both negative, the switching control section outputs the control signal to control the switching section to turn the first type of switching element ON, andwherein the switching control section outputs the control signal to control the switching section so as to avoid turning ON both of the first and second types of switching elements that are associated with the same phase at the same time, andwherein the switching control section performs the pulse density modulation based on a space vector modulation.
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Accused Products
Abstract
The AC converter converts a single-phase input AC voltage with a frequency f0 into a three-phase output AC voltage with a frequency f1 that is lower than f0. The AC converter includes a switching section 101 with multiple switching elements and a switching control section 103 that controls the conduction states of the respective switching elements. The switching control section 103 supplies pulses that have been subjected to a pulse density modulation based on space vector modulation to the switching section 101, thereby getting the conversion into a three-phase output AC voltage done.
17 Citations
11 Claims
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1. An AC converter that converts a single-phase input AC voltage with a frequency f0 into a three-phase output AC voltage with a frequency f1 that is lower than f0, the converter comprising:
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a switching section that converts the input AC voltage in response to a control signal and that outputs the converted voltage to a phase that has been selected in accordance with the control signal; a filter section that filters out high frequency components from the converted voltage, thereby converting the converted voltage into the output AC voltage; and a switching control section that performs a pulse density modulation on a phase-by-phase basis and based on a reference signal with the frequency f1 which is associated with the output AC voltage of each said phase, synchronously with a zero cross of the input AC voltage, thereby generating the control signal according to a pulse generation status by the pulse density modulation and the polarity of the input AC voltage and sending out the control signal to the switching section, and wherein the switching section includes a first type of switching element that applies a positive voltage to its associated phase if the polarity of the input AC voltage is positive and a second type of switching element that applies a positive voltage to its associated phase if the polarity of the input AC voltage is negative, and wherein if the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are both positive, the switching control section outputs the control signal to control the switching section to turn the first type of switching element ON, and if the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are negative and positive, respectively, the switching control section outputs the control signal to control the switching section to turn the second type of switching element ON, and if the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are positive and negative, respectively, the switching control section outputs the control signal to control the switching section to turn the second type of switching element ON, and if the polarities of the input AC voltage and the reference signal for use in the pulse density modulation are both negative, the switching control section outputs the control signal to control the switching section to turn the first type of switching element ON, and wherein the switching control section outputs the control signal to control the switching section so as to avoid turning ON both of the first and second types of switching elements that are associated with the same phase at the same time, and wherein the switching control section performs the pulse density modulation based on a space vector modulation. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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2. An AC converter that converts a single-phase input AC voltage with a frequency f0 into a three-phase output AC voltage with a frequency f1 that is lower than f0, the converter comprising:
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a converter section that converts the input AC voltage into a DC voltage; a switching section that converts the DC voltage in response to a control signal and that outputs the converted voltage to a phase that has been selected in accordance with the control signal; a filter section that filters out high frequency components from the converted voltage, thereby converting the converted voltage into the output AC voltage; and a switching control section that performs a pulse density modulation on a phase-by-phase basis and based on a reference signal with the frequency f1, which is associated with the output AC voltage of each said phase, synchronously with a zero cross of the input AC voltage, thereby generating the control signal according to a pulse generation status by the pulse density modulation and sending out the control signal to the switching section, wherein the switching section includes a first type of switching element that applies a positive voltage to its associated phase if the polarity of the input AC voltage is positive and a second type of switching element that applies a positive voltage to its associated phase if the polarity of the input AC voltage is negative, and wherein if the polarity of the reference signal for use in the pulse density modulation is positive, the switching control section outputs the control signal to control the switching section to turn the first type of switching element ON, and wherein if the polarity of the reference signal for use in the pulse density modulation is negative, the switching control section outputs the control signal to control the switching section to turn the second type of switching element ON, and wherein the switching control section outputs the control signal to control the switching section so as to avoid turning ON both of the first and second types of switching elements that are associated with the same phase at the same time, and wherein the switching control section performs the pulse density modulation based on a space vector modulation. - View Dependent Claims (3, 4)
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Specification