High frequency AC/AC converter with PF correction
First Claim
1. A high frequency converter apparatus comprising:
- first and second input terminals for connection to a source of DC supply voltage for the converter,output means including a resonant circuit for connection to a load to be driven by the converter,first and second controlled switching devices of the same type,a first series circuit including an inductor, a rectifier element, and said first controlled switching device coupled to said input terminals such that current flows from the input terminals through the rectifier element when the first controlled switching device is conductive,a storage capacitor coupled to said rectifier element and to said output means,said second controlled switching device being coupled to said storage capacitor,first and second diodes coupled across said first and second controlled switching devices, respectively, anda control circuit responsive at least to a voltage developed across the storage capacitor and having output means coupled to control electrodes of the first and second controlled switching devices so as to alternately trigger the first and second controlled switching devices on and off at a high frequency, said first switching device providing power factor correction and also being a part of a high frequency DC/AC inverter.
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Abstract
A high frequency AC/AC converter apparatus with power factor correction includes an AC/DC converter circuit part to provide power factor correction and a DC/AC inverter circuit part to produce a high frequency AC signal for operation of a load, for example, a discharge lamp. The AC/DC converter circuit part includes a diode and an inductor. The converter apparatus utilizes first and second semiconductor controlled switching devices, one of which is common to each part of the overall converter apparatus. A single control circuit controls both parts of the converter apparatus by controlling the switching of the first and second semiconductor switching devices. There are two possible control techniques, constant duty ratio control or duty ratio sweeping control. A voltage clamp circuit inhibits undesired oscillation of the diode voltage.
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Citations
34 Claims
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1. A high frequency converter apparatus comprising:
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first and second input terminals for connection to a source of DC supply voltage for the converter, output means including a resonant circuit for connection to a load to be driven by the converter, first and second controlled switching devices of the same type, a first series circuit including an inductor, a rectifier element, and said first controlled switching device coupled to said input terminals such that current flows from the input terminals through the rectifier element when the first controlled switching device is conductive, a storage capacitor coupled to said rectifier element and to said output means, said second controlled switching device being coupled to said storage capacitor, first and second diodes coupled across said first and second controlled switching devices, respectively, and a control circuit responsive at least to a voltage developed across the storage capacitor and having output means coupled to control electrodes of the first and second controlled switching devices so as to alternately trigger the first and second controlled switching devices on and off at a high frequency, said first switching device providing power factor correction and also being a part of a high frequency DC/AC inverter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A high-frequency electronic apparatus comprising:
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first and second input terminals for supplying a low frequency pulsating DC voltage to the high-frequency apparatus, first and second semiconductor controlled switching devices, an inductor, a rectifier element, an energy storage capacitor, means for coupling said first and second semiconductor controlled switching devices, said inductor, said rectifier element and said energy storage capacitor in circuit to said input terminals so as to form a high-frequency DC/AC inverter circuit, and a control circuit having output means coupled to control electrodes of the first and second semiconductor controlled switching devices so as to alternately trigger said first and second semiconductor controlled switching devices on and off at a high-frequency, said control circuit including means for triggering said first and second semiconductor controlled switching devices to produce a duty cycle that repetitively sweeps between a maximum duty cycle value and a minimum duty cycle value at a low frequency. - View Dependent Claims (18, 19)
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20. An electronic apparatus as claimed in claim further comprising output means includes an LC resonant circuit having a resonant frequency below the switching frequency of said first and second semiconductor controlled switching devices.
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21. A power supply for deriving a high frequency AC voltage for a load from a DC supply voltage comprising:
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first and second input terminals for connection to a source of pulsating DC supply voltage, means coupling said input terminals to a circuit comprising an inductor, a rectifier element, a first switching transistor, a storage capacitor and a first diode connected together so that when the first switching transistor is turned on current flows from the input terminals through the first switching transistor, the inductor and the rectifier element and when the first switching transistor is turned off the inductor supplies a charge current to the storage capacitor via said first diode, a DC/AC inverter circuit coupled to said storage capacitor and comprising a second switching transistor, said first switching transistor, and output means for connection to said load, and a control circuit independent of an input voltage at said input terminals and responsive at least to a voltage on the storage capacitor and having an output coupled to the control electrodes of the first and second switching transistors so as to alternately trigger said first and second switching transistors on and off at a high frequency. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification