CN103391014B - power conversion device - Google Patents

Abstract

The invention discloses a power supply conversion device which is used for driving an electronic load and comprises a rectification module, an active switch element, a driving module, an input voltage detection module, an output voltage detection module, a current detection module and a digital processing module. The active switching element is connected in parallel to the electronic load. The input voltage detection module is used for sampling the input sampling voltage waveform. The output voltage detection module is used for sampling the output sampling voltage waveform. The current detection module is used for sampling the actual input current waveform. The digital processing module generates a current reference command according to the input sampling voltage waveform and the output sampling voltage waveform, and the digital processing module dynamically switches the conduction state of the active switch element according to the current reference command and the actual input current waveform.

Description

power conversion device

technical field

The present disclosure relates to a power conversion device, and more particularly to a power conversion device with a power factor correction function.

Background technique

Due to the energy crisis in recent years, in addition to the development of new energy sources, countries have increasingly stringent requirements on existing electrical products, especially power factor and total harmonic distortion. In new power standards (such as IEC61000- 3-12 specification) has certain requirements on the total current harmonic distortion, which affects the designer's design considerations in the product.

General electrical equipment is often not purely resistive, but whether it is inductive or capacitive, it will lead to poor power factor. Poor power factor will lead to an increase in input current and increase the burden on the power supply system. In addition, the input current Severe distortion, including a large number of harmonic components, will cause serious pollution to the power grid.

Therefore, if the power factor of the electrical equipment can be improved and the harmonic distortion can be reduced, it will bring great help to the quality of the power supply system. Existing power factor improvement circuits can be divided into two categories: passive and active. Passive power factor improvement circuits use passive components (such as inductors and capacitors) to improve the power factor. Although the structure is simple, it is bulky and the power factor correction The effect is limited and other shortcomings.

The active power factor improvement circuit mainly uses an external circuit to achieve the purpose of power factor correction. Compared with the passive type, it has the advantages of small size, light weight and high power factor. However, most of the existing active power factor improvement circuits Complicated external circuits are required, and readjustment or design is required for different harmonic components.

Contents of the invention

In order to solve the above problems, the purpose of the present invention is to provide a circuit structure of a power conversion device to achieve power factor correction and improve the efficacy of input current harmonics, so that it can meet the power standard. In the prior art, the rectified input voltage waveform is sent to the controller to generate the current reference command, but this method will lead to poor current harmonic reduction effect. In order to improve this shortcoming, the present invention sends the input voltage waveform obtained by the input voltage detection device to a digital processing module for pre-processing and frequency adjustment to generate a reference voltage waveform. The purpose is to finally make the actual input current follow the reference voltage waveform. In this way, the switching signal required by the active switching element is generated, thereby achieving the purpose of improving the power factor and reducing the current harmonic.

One mode of the present disclosure is to provide a power conversion device for coupling and driving an electronic load. The power conversion device includes a rectifier module, an active switching element, an input voltage detection module, and an output voltage detection module. module, a current detection module and a digital processing module. The rectification module is coupled with an AC power input. The active switching element is coupled between the rectification module and the electronic load, and the two ends of the active switching element are connected in parallel to the two ends of the electronic load. The input voltage detection module is coupled between the rectification module and the active switch element for sampling an input sampling voltage waveform. The output voltage detection module is coupled between the active switch element and the electronic load, and is used for sampling an output sampling voltage waveform. The current detection module is coupled to the active switch element for sampling an actual input current waveform. The digital processing module is coupled to the input voltage detection module, the output voltage detection module and the current detection module. The digital processing module generates a current reference command according to the input sampling voltage waveform and the output sampling voltage waveform. The digital processing module generates a current reference command according to the The current reference command and the actual input current waveform dynamically switch the active switching element.

According to an embodiment of the invention, the active switching element is a silicon carbide switch.

According to an embodiment of the present invention, the digital processing module includes a reference voltage waveform generator, an output voltage feedback regulator and a current reference command generator. The reference voltage waveform generator is coupled with the input voltage detection module and is used for processing the input sampled voltage waveform and generating a reference voltage waveform. The output voltage feedback regulator is coupled with the output voltage detection module and used for generating a control signal according to the output sampled voltage waveform. The current reference command generator is respectively coupled to the reference voltage waveform generator and the output voltage feedback regulator, and the current reference command generator generates the current reference command according to the reference voltage waveform and the control signal.

According to an embodiment of the present invention, the reference voltage waveform generated by the reference voltage waveform generator determines a current pulse width of the current reference command.

According to an embodiment of the present invention, the control signal generated by the output voltage feedback regulator determines a current magnitude of the current reference command.

According to an embodiment of the present invention, the reference voltage waveform generator generates a reference voltage waveform according to the input sampling voltage waveform, and the frequency of the reference voltage waveform is lower than the frequency of the input sampling voltage waveform.

According to an embodiment of the present invention, the digital processing module further includes a driving module, a current feedback regulator and a switching signal generator. The driving module is coupled to the control end of the active switching element. The current feedback regulator is coupled to the current detection module and the current reference command generator. The current feedback regulator adjusts the current reference command according to the actual input current waveform sampled by the current detection module, and then generates a switch modulation signal. The switch signal generator is coupled to the current feedback regulator, and the switch signal generator generates a switch signal to the drive module according to the switch modulation signal, so as to dynamically switch the active switch element through the drive module.

According to an embodiment of the present invention, the current feedback regulator continuously adjusts the current reference command to control the active switching device until the actual input current waveform follows (or aligns with) the reference voltage waveform.

According to an embodiment of the present invention, the power conversion device further includes a capacitive element and an inductive element, the capacitive element is connected in parallel with the electronic load, and the inductive element is connected in series with the electronic load.

According to an embodiment of the present invention, the power conversion device further includes a passive switch element, and the passive switch element is connected in series between the inductance element and the electronic load.

According to an embodiment of the present invention, the power conversion device further includes another active switching element, and the other active switching element is connected in series between the inductance element and the electronic load.

According to an embodiment of the present invention, the AC power input is a three-phase AC power input.

One aspect of the present disclosure is to provide a power conversion device for coupling and driving an electronic load. The power conversion device includes a rectification module, an active switching element, a state detection module and a digital processing module. The rectification module is coupled with an AC power input. The active switching element is coupled between the rectification module and the electronic load, and the active switching element is connected in parallel with the electronic load. The state detecting module is coupled between the rectifying module and the electronic load, and is used for detecting the state of the power conversion device and correspondingly outputting an input sampled voltage waveform, an output sampled voltage waveform and an actual input current waveform. The digital processing module receives the input sampled voltage waveform, the output sampled voltage waveform and the actual input current waveform. Wherein, after the digital processing module uses the input sampling voltage waveform to generate a reference voltage waveform, it generates a current reference command and then controls the active switching element until the actual input current waveform follows the reference voltage waveform.

Description of drawings

In order to make the above and other objects, features, advantages and embodiments of the present disclosure more comprehensible, the accompanying drawings are described as follows:

FIG. 1 is a schematic diagram of a power conversion device according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the input sampling voltage waveform generated by the input voltage detection module in FIG. 1;

Fig. 3 is a functional block diagram of a digital processing module according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a reference voltage waveform generated by the reference voltage waveform generator in FIG. 3;

5 is a schematic diagram of comparison of the waveform of the actual input current sampled by the current detection module, the voltage waveform of the power signal, the current waveform of the power signal, and the reference voltage waveform in this embodiment;

6 is a schematic diagram of a power conversion device according to another embodiment of the present invention; and

FIG. 7 is a functional block diagram of the digital processing module and its peripheral components in the embodiment of FIG. 6 .

Wherein, the reference signs are explained as follows:

100,102: power conversion device;

200: AC power input;

202: driving an electronic load;

110: rectification module;

S1: active switching element;

S2: switch element;

C1, C2: capacitive elements;

L1: inductance element;

167: drive module;

130: input voltage detection module;

140: output voltage detection module;

150: current detection module;

160: digital processing module;

204: power signal;

132: input sampling voltage;

142: output sampling voltage;

152: actual input current;

162: reference voltage waveform generator;

164: output voltage feedback regulator;

166: current reference command generator;

168: current feedback regulator;

169: switch signal generator;

161: control signal;

163: reference voltage waveform;

165: current reference command;

170: switch modulation signal;

190: a state detection module.

detailed description

Please refer to FIG. 1 , which is a schematic diagram of a power conversion device 100 according to a preferred embodiment of the present invention. The power conversion device 100 receives an AC power input 200 to drive an electronic load 202, wherein, in this preferred embodiment, the AC power input 200 is a three-phase AC power input.

As shown in FIG. 1 , the power conversion device 100 includes a rectification module 110 , an active switching element S1 , an input voltage detection module 130 , an output voltage detection module 140 , a current detection module 150 and a digital processing module 160 .

The rectification module 110 is coupled to the AC power input 200 . The active switching element S1 is coupled between the rectification module 110 and the electronic load 202 , and both ends of the active switching element S1 are connected in parallel to both ends of the electronic load 202 . In this embodiment, the active switching element S1 may further be a silicon carbide switch, but the invention is not limited thereto.

The digital signal processor 160 is coupled to the control terminal of the active switch element S1 for controlling the conduction state of the active switch element S1 , including the conduction state and the disconnection state. In this preferred embodiment, the power conversion device 100 further includes a capacitive element C1 and an inductive element L1 , wherein the capacitive element C1 is connected in parallel with the electronic load 202 , and the inductive element L1 is connected in series with the electronic load 202 . Wherein, when the digital signal processor 160 switches the active switching element S1 to the off state, the capacitive element C1 and the inductive element L1 can form a traditional inductance-capacitance filter circuit (LC filter) with a fixed filter coefficient. When the digital signal processor 160 switches the active switching element S1 to the conduction state, the operating characteristics of the inductor-capacitor filter circuit can be dynamically adjusted, thereby achieving a power factor correction function.

In addition, in practical applications, the power conversion device 100 may further include another capacitive element C2 coupled to the input terminal for high-frequency filtering.

The AC power input 200 can provide a three-phase input AC power signal 204 to the power conversion device 100 . The rectification module 110 can rectify the power signal 204 provided by the AC power input 200 .

The input voltage detection module 130 is coupled between the rectification module 110 and the active switching element S1 , the input voltage detection module 130 samples the rectified power signal and generates a waveform of the input sampling voltage 132 . The output voltage detection module 140 is coupled between the active switch element S1 and the electronic load 202 for sampling the waveform of the output sampling voltage. The current detection module 150 is coupled to the active switch element S1 for sampling the waveform of the actual input current 152 .

Please also refer to FIG. 2 , which is a schematic diagram of the waveform of the input sampling voltage 132 generated by the input voltage detection module 130 in FIG. 1 . FIG. 2 shows the waveform of the input sample voltage 132 and the three-phase voltage waveform of the power signal 204 provided by the AC power input 200 .

As shown in FIG. 2 , after the AC power signal is rectified by the rectification module 110 , the waveform of the input sampling voltage 132 generated by sampling by the input voltage detection module 130 is a waveform of a high frequency signal input sampling voltage 132 . In this preferred embodiment, the waveform of the input sampling voltage 132 is sent to the digital processing module 160 for further processing, and the specific processing methods are described in detail in the following paragraphs.

The digital processing module 160 is coupled to the input voltage detection module 130 , the output voltage detection module 140 and the current detection module 150 . Please also refer to FIG. 3 , which is a functional block diagram of the digital processing module 160 according to a preferred embodiment of the present invention.

As shown in FIG. 3 , the digital processing module 160 includes a reference voltage waveform generator 162 , an output voltage feedback regulator 164 , a current reference command generator 166 , a current feedback regulator 168 , a switching signal generator 169 and a driving module 167 .

The driving module 167 is coupled to the control terminal of the active switching element S1 to control the conduction state of the active switching element S1, including the conducting state and the disconnecting state. The digital signal processor 160 switches the active switching element through the driving module 167 S1.

Wherein, the reference voltage waveform generator 162 is coupled to the input voltage detection module 130 . The output voltage feedback regulator 164 is coupled to the output voltage detection module 140, and the reference voltage waveform generator 162, the output voltage feedback regulator 164, the current reference command generator 166, the current feedback regulator 168 and the switch signal generator 169 are It is packaged and covered by a processor, but this technology is understood by those skilled in the art, so the specific circuit logic thereof will not be described in detail here.

The reference voltage waveform generator 162 generates a reference voltage waveform 163 according to the waveform of the input sampling voltage 132 sampled by the input voltage detection module 130, please refer to FIG. 4 , which is the reference voltage waveform 163 generated by the reference voltage waveform generator 162 in FIG. 3 schematic diagram. The frequency of the reference voltage waveform 163 produced by the reference voltage waveform generator 162 is lower than the waveform of the input sampling voltage 132. As shown in FIG. The present invention is not limited thereto.

Generally speaking, the frequency of the waveform of the input sampling voltage 132 is usually greater than the variation frequency of the current waveform, and the frequency of the reference voltage waveform 163 generated by the reference voltage waveform generator 162 should be closer to the variation frequency of the three-phase voltage waveform of the input power signal 204 , in order to facilitate subsequent power factor adjustment.

Please also refer to FIG. 5 , which is a comparison diagram of the waveform of the actual input current 152 sampled by the current detection module 150 , the voltage waveform of the power signal 204 , the current waveform of the power signal 204 , and the reference voltage waveform 163 in this preferred embodiment.

The current reference command generator 166 is coupled to the reference voltage waveform generator 162 and the output voltage feedback regulator 164 respectively. Wherein, the output voltage feedback regulator 164 is coupled to the output voltage detection module 140 for generating the control signal 161 according to the waveform of the output sampling voltage 142 .

The current reference command generator 166 generates the current reference command 165 according to the product of the reference voltage waveform 163 output by the reference voltage waveform generator 162 and the control signal 161 output by the output voltage feedback regulator 164 .

Wherein, the reference voltage waveform 163 generated by the reference voltage waveform generator 162 (as shown in FIG. 4 and FIG. 5 ) determines the current pulse width of the current reference command 165. In addition, the reference voltage waveform generator 162 is used to process the input sampling voltage 132 waveform, and reduce the frequency of the waveform of the input sampling voltage 132 . The control signal 161 output by the output voltage feedback regulator 164 determines the current magnitude of the current reference command 165 . The purpose of the current reference command 165 is to make the input current of the power conversion device 100 (refer to the waveform of the actual input current 152 in FIG. 5 ) track (or align) with the reference voltage waveform 163 . In this way, the power factor of the power conversion device 100 can be optimized to achieve the best power conversion effect.

In addition, the current feedback regulator 168 in the digital processing module 160 is coupled to the current detection module 150 and the current reference command generator 166. The current feedback regulator 168 adjusts the current reference command according to the waveform of the actual input current 152 sampled by the current detection module 150. 165.

In this embodiment, the current feedback regulator 168 in the digital processing module 160 processes the current reference command 165 and the waveform of the actual input current 152 to generate the switch modulation signal 170 .

The switching signal generator 169 is coupled to the current feedback regulator 168 , and the switching signal generator 169 generates a switching signal to the driving module 167 according to the switching modulation signal 170 , so as to dynamically adjust the active switching element S1 through the driving module 167 .

The current feedback regulator 168 can continue to make feedback adjustments to the current reference command until the actual input current waveform 152 tracks the frequency of the reference voltage waveform 163 . That is, the power factor of the power conversion device 100 is optimized to achieve the best power conversion effect.

In this embodiment, the active switching element S1 with high frequency switching is adopted, and the inductance element L1 with large inductance or the capacitance element C1 with large capacitance is not required, so that the volume of the inductance element L1 and the capacitance element C1 can be reduced. In addition, the reference voltage waveform 163 (as shown in FIG. 4 ) is generated programmable by the digital processing module 160 , which greatly improves the plasticity of power factor improvement.

In this embodiment, the power conversion device 100 is not limited to include a single active switching element S1. In this embodiment, the power conversion device 100 may further include a switching element S2, wherein the switching element S2 is connected in series with the inductance element L1 and the electronic Sex load between 202. The switching element S2 can be a passive switching element, or can also be an active switching element. In a preferred embodiment, the switching element S2 is a diode.

In addition, the power conversion device 100 of this case has circuit variability, and can choose a traditional inductance-capacitor filter circuit (disconnecting S1) or a power factor improvement circuit (switching the conduction state of S1), and has a boost function. There are technical comparisons, which improve the convenience of using the circuit.

In addition, the internal circuit elements of the power conversion device of the present invention are not limited to the embodiment shown in FIG. 1 and FIG. 3 , please refer to FIG. 6 and FIG. 7 , FIG. 6 is a A schematic diagram of the power conversion device 102 , FIG. 7 is a functional block diagram of the digital processing module 160 and its peripheral components in the embodiment of FIG. 6 .

As shown in FIG. 6 , in this embodiment, the power conversion device 102 includes a rectification module 110 , an active switching element S1 , a state detection module 190 and a digital processing module 160 . The rectification module 110 is coupled to the AC power input 200 . The active switching element S1 is coupled between the rectification module 110 and the electronic load 202 , and the active switching element S1 is connected in parallel with the electronic load 202 .

It should be noted that in this embodiment, the state detection module 190 is coupled between the rectification module 110 and the electronic load 202, and the state detection module 190 is used to detect the state of the power conversion device 102 and output an input sampling voltage accordingly The waveform of 132 , the waveform of the output sampling voltage 142 and the waveform of the actual input current 152 are shown in FIG. 6 and FIG. 7 .

The digital processing module 160 receives the waveform of the input sampling voltage 132 , the waveform of the output sampling voltage 142 and the waveform of the actual input current 152 .

As shown in FIG. 7 , the digital processing module 160 includes a reference voltage waveform generator 162 , an output voltage feedback regulator 164 , a current reference command generator 166 , a current feedback regulator 168 , a switching signal generator 169 and a driving module 167 . Wherein, the reference voltage waveform generator 162 , the output voltage feedback regulator 164 and the current feedback regulator 168 are respectively coupled to the state detection module 190 .

The reference voltage waveform generator 162 receives the waveform of the input sampling voltage 132 from the state detection module 190 . The output voltage feedback regulator 164 receives the waveform of the output sampling voltage 142 from the state detection module 190 . The current feedback regulator 168 receives the waveform of the actual input current 152 from the state detection module 190 .

Wherein, the digital processing module 160 generates a current reference command 165 after using the waveform of the input sampling voltage 132 to generate a reference voltage waveform 163 (refer to FIG. 4 and FIG. 5 of the previous embodiment together) (refer to FIG. 5 of the previous embodiment together). FIG. 5 ) and then control the active switching element S1 until the waveform of the actual input current 152 follows the reference voltage waveform 163 .

In addition, the operating principle and signal processing content of the power conversion device 102 and the digital processing module 160 in this embodiment are roughly similar to the power conversion device 100 in the previous embodiment. Please refer to the previous embodiment and FIGS. The content corresponding to FIG. 5 will not be repeated here.

To sum up, this disclosed document proposes a circuit structure of a power conversion device to achieve power factor correction and improve the effect of input current harmonics, so that it can meet the power standard. In the invention, the input voltage waveform obtained by the input voltage detection device is sent to a digital processing module for pre-processing for frequency adjustment, and the change frequency of the input voltage waveform is adjusted to be consistent with the current change frequency. In this way, the switching signal required by the active switching element is generated, thereby achieving the purpose of improving the power factor and reducing the current harmonic.

Although the present disclosure has been disclosed above in terms of implementation, it is not intended to limit the present disclosure. Any person skilled in the art may make various modifications and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be defined by the appended application claims.

Claims (19)

1. A power conversion device for coupling and driving an electronic load, the power conversion device comprising: A rectifier module, coupled with an AC power input; an active switching element, coupled between the rectifier module and the electronic load, and the two ends of the active switching element are connected in parallel to the two ends of the electronic load; An input voltage detection module, coupled between the rectification module and the active switching element, for sampling an input sampling voltage waveform; An output voltage detection module, coupled between the active switching element and the electronic load, for sampling an output sampling voltage waveform; a current detection module, coupled to the active switching element, for sampling an actual input current waveform; and A digital processing module, coupled to the input voltage detection module, the output voltage detection module, the current detection module and a control terminal of the active switching element, the digital processing module according to the input sampling voltage waveform and the output sampling voltage The waveform generates a current reference command, and the digital processing module dynamically switches the active switching element according to the current reference command and the actual input current waveform; Wherein the digital processing module includes: A reference voltage waveform generator, coupled to the input voltage detection module, for processing the input sample voltage waveform and generating a reference voltage waveform, wherein the frequency of the reference voltage waveform is lower than the frequency of the input sample voltage waveform; an output voltage feedback regulator, coupled to the output voltage detection module, for generating a control signal according to the output sampled voltage waveform; and A current reference command generator is coupled to the reference voltage waveform generator and the output voltage feedback regulator respectively, and the current reference command generator generates the current reference command according to the reference voltage waveform and the control signal. 2. The power conversion device as claimed in claim 1, wherein the reference voltage waveform generated by the reference voltage waveform generator determines a current pulse width of the current reference command. 3. The power conversion device as claimed in claim 1, wherein the control signal generated by the output voltage feedback regulator determines a current magnitude of the current reference command. 4. The power conversion device as claimed in claim 1, wherein the digital processing module further comprises: a driving module, coupled to the control end of the active switching element; A current feedback regulator, coupled with the current detection module and the current reference command generator, the current feedback regulator adjusts the current reference command according to the actual input current waveform sampled by the current detection module, and then generates a switch modulation signal; and A switch signal generator is coupled with the current feedback regulator, and the switch signal generator generates a switch signal to the drive module according to the modulated signal of the switch, so as to dynamically switch the active switch element through the drive module. 5. The power conversion device as claimed in claim 4, wherein the current feedback regulator continuously adjusts the current reference command to control the active switching device until the actual input current waveform follows the reference voltage waveform. 6. The power conversion device according to claim 1, further comprising a capacitive element and an inductive element, the capacitive element is connected in parallel with the electronic load, and the inductive element is connected in series with the electronic load. 7. The power conversion device as claimed in claim 6, further comprising a passive switching element connected in series between the inductive element and the electronic load. 8. The power conversion device as claimed in claim 6, further comprising another active switching element, the other active switching element is connected in series between the inductive element and the electronic load. 9. The power conversion device as claimed in claim 1, wherein the AC power input is a three-phase AC power input. 10. The power conversion device as claimed in claim 1, wherein the active switching element is a silicon carbide switch. 11. A power conversion device for coupling and driving an electronic load, the power conversion device comprising: A rectifier module, coupled with an AC power input; an active switching element, coupled between the rectifier module and the electronic load, and the active switching element is connected in parallel with the electronic load; A state detection module, coupled between the rectifier module and the electronic load, is used to detect the state of the power conversion device and correspondingly output an input sampled voltage waveform, an output sampled voltage waveform and an actual input current waveform; and A digital processing module, receiving the input sampling voltage waveform, the output sampling voltage waveform and the actual input current waveform; Wherein, the digital processing module uses the input sampling voltage waveform to generate a reference voltage waveform, and then generates a current reference command to control the active switching element until the actual input current waveform follows the reference voltage waveform; Wherein the digital processing module includes: A reference voltage waveform generator, coupled to the state detection module, for processing the input sampled voltage waveform and generating the reference voltage waveform, wherein the frequency of the reference voltage waveform is lower than the frequency of the input sampled voltage waveform; an output voltage feedback regulator, coupled to the state detection module, for generating a control signal according to the output sampled voltage waveform; and A current reference command generator is coupled to the reference voltage waveform generator and the output voltage feedback regulator respectively, and the current reference command generator generates the current reference command according to the reference voltage waveform and the control signal. 12. The power conversion device as claimed in claim 11, wherein the reference voltage waveform generated by the reference voltage waveform generator determines a current pulse width of the current reference command. 13. The power conversion device as claimed in claim 11, wherein the control signal generated by the output voltage feedback regulator determines a current magnitude of the current reference command. 14. The power conversion device as claimed in claim 11, wherein the digital processing module further comprises: a driving module, coupled to the control terminal of the active switching element; A current feedback regulator, coupled with the state detection module and the current reference command generator, the current feedback regulator adjusts the current reference command according to the actual input current waveform generated by the state detection module, and then generates a switch modulation signal; and A switch signal generator is coupled with the current feedback regulator, and the switch signal generator generates a switch signal to the drive module according to the modulated signal of the switch, so as to dynamically switch the active switch element through the drive module. 15. The power conversion device as claimed in claim 14, wherein the current feedback regulator continuously adjusts the current reference command to control the active switching device until the actual input current waveform follows the reference voltage waveform. 16. The power conversion device as claimed in claim 11, further comprising a capacitive element and an inductive element, the capacitive element is connected in parallel with the electronic load, and the inductive element is connected in series with the electronic load. 17. The power conversion device as claimed in claim 16, further comprising a passive switching element connected in series between the inductive element and the electronic load. 18. The power conversion device as claimed in claim 16, further comprising another active switching element connected in series between the inductive element and the electronic load. 19. The power conversion device as claimed in claim 11, wherein the AC power input is a three-phase AC power input.