JP6802048B2 - Control device - Google Patents

Description

The present invention relates to a control device that controls a series resonance type power supply device.

Conventionally, a series resonance type power supply device as shown in FIG. 4 is known (see, for example, Patent Document 1). The series resonance type power supply device 100 shown in FIG. 4 has an inverter circuit 200 that converts input DC power into AC power, a series resonance circuit 300 connected to the inverter circuit 200, and insulation connected to the series resonance circuit 300. It includes a transformer 400 and a rectifying and smoothing circuit 500 connected to a secondary winding of the insulated transformer 400. The inverter circuit 200 includes four known semiconductor switching elements 201 to 204. The series resonance circuit 300 is configured by connecting the coil 301 and the capacitor 302 in series. The rectifying and smoothing circuit 500 includes a bridge-type full-wave rectifying circuit 501 and a smoothing capacitor 502, and converts AC power obtained from the insulated transformer 400 into DC power and outputs it. Further, the series resonance type power supply device 100 shown in FIG. 4 includes a control device 600 that generates a gate signal to be supplied to the gate electrodes of the semiconductor switching elements 201 to 204 of the inverter circuit 200.

Japanese Unexamined Patent Publication No. 2013-226002

As a control method of the series resonance type power supply device 100 shown in FIG. 4, the output pulse command of the inverter circuit 200 is a pulse waveform having an odd multiple width of half the resonance period of the series resonance circuit 300 as shown in FIG. There is a control method to be combined. According to this method, switching can be performed with zero current, and operation can be performed with low power loss.

However, in the control method described above, in the region where the pulse width of the output pulse command of the inverter circuit 200 becomes long and the current flowing between the insulating transformer 400 and the rectifying smoothing circuit 500 becomes discontinuous during light load operation, The resonance frequency of the series resonance circuit 300 changes due to the exciting inductance of the insulation transformer 400. By changing the resonance frequency of the series resonance circuit 300, the period of the inverter current flowing through the inverter circuit 200 changes.

FIG. 6 is a diagram showing an inverter output command and an inverter current during light load operation. When the cycle of the inverter current flowing through the inverter circuit 200 changes, switching is performed at the timing when the inverter current is not zero (timing when the inverter circuit 200 is not zero current) as shown by the dotted circles in FIG. 6, and the switching loss. There is a problem that the number increases.

An object of the present invention is to solve the above-mentioned problems and to provide a control device capable of suppressing an increase in switching loss even during light load operation of a series resonance type power supply device.

In order to solve the above problems, the control device according to the present invention is a control device that controls a series resonance type power supply device including an inverter circuit having a plurality of switching elements and a series resonance circuit connected to the inverter circuit. The control amount calculation unit that calculates the control amount for obtaining a desired output based on the feedback signal of the output voltage of the series resonance type power supply device and the control amount calculated by the control amount calculation unit are described above. the output pulse command of the inverter circuit forms the raw, so that the output pulses corresponding to the output pulse command thus generated is output from the inverter circuit, a gate signal generator for generating a gate signal to the plurality of switching elements, The gate signal generation unit has a buffer variable obtained by adding the control amount every half of the resonance period of the series resonant circuit to a predetermined value or more, and the pulse width of the output pulse command of the inverter circuit is increased. When it is an odd multiple of the half cycle of the resonance cycle of the series resonance circuit, the gate signal that inverts the output pulse of the inverter circuit is generated, and the pulse width of the output pulse command is the resonance cycle of the series resonance circuit. If it exceeds half, three times, the inverter circuit is put into a gate block state.

Further, in the control device according to the present invention, when the pulse width of the output pulse command exceeds three times half of the resonance period of the series resonance circuit, the gate signal generation unit reverses the output pulse command. It is desirable to keep the inverter circuit in the gate block state until the output pulse command in the direction is output.

According to the control device according to the present invention, it is possible to suppress an increase in switching loss even during light load operation of the series resonance type power supply device.

It is a figure which shows the structural example of the series resonance type power supply device which concerns on one Embodiment of this invention. It is a figure for demonstrating the method of generating the output pulse command by the gate signal generation part shown in FIG. It is a figure which shows an example of the waveform of the output pulse command generated by the gate signal generation part shown in FIG. 1 and the inverter power flowing through an inverter circuit. It is a figure which shows the structural example of the conventional series resonance type power supply apparatus. It is a figure which shows an example of the waveform of the output pulse command and the inverter current of the inverter circuit shown in FIG. It is a figure which shows an example of the waveform of the output pulse command and the inverter current of the inverter circuit shown in FIG.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a diagram showing a configuration example of a series resonance type power supply device 10 according to an embodiment of the present invention.

The series resonance type power supply device 10 shown in FIG. 1 has an inverter circuit 20 that converts input DC power into AC power, a series resonance circuit 30 connected to the inverter circuit 20, and insulation connected to the series resonance circuit 30. A transformer 40, a rectifying smoothing circuit 50 connected to a secondary winding of the insulated transformer 40, and a control device 60 are provided. The inverter circuit 20 has four known semiconductor switching elements (switching elements) 21 to 24 and diodes connected in antiparallel to each of the semiconductor switching elements 21 to 24. The series resonance circuit 30 is configured by connecting the coil 31 and the capacitor 32 in series. The rectifying and smoothing circuit 50 includes a bridge-type full-wave rectifying circuit 51 and a smoothing capacitor 52, and converts AC power obtained from the insulating transformer 40 into DC power and outputs it.

The control device 60 includes a control amount calculation unit 61 and a gate signal generation unit 62.

The control amount calculation unit 61 receives a feedback signal indicating the output voltage of the rectifying smoothing circuit 50, and calculates a control amount for obtaining a preset desired output voltage based on the feedback signal. The control amount calculation unit 61 outputs the calculated control amount to the gate signal generation unit 62.

The gate signal generation unit 62 generates an output pulse command of the inverter circuit 20 based on the calculation amount output from the control amount calculation unit 61, and outputs an output pulse corresponding to the generated output pulse command from the inverter circuit 20. As described above, the gate signal for the switching elements 21 to 24 of the inverter circuit 20 is generated. The gate signal generated by the gate signal generation unit 62 is input to the gate electrodes of the semiconductor switching elements 21 to 24 of the inverter circuit 20.

The control amount calculation unit 61 calculates the control amount as a real number from 0 to 1. The gate signal generation unit 62 adds the control amount calculated by the control amount calculation unit 61 every half time of the resonance cycle of the series resonance circuit 30. In the following description, this added value is referred to as a buffer variable for convenience. As shown in FIG. 2, the gate signal generation unit 62 uses the buffer variable when the buffer variable is 1 or more and the pulse width of the output pulse command is an odd multiple of half the resonance cycle of the series resonance circuit 30. 1 is subtracted, and a gate signal that inverts the output pulse command of the inverter circuit 20 is generated. As a result, the output pulse command of the inverter circuit 20 can be generated by a combination of pulse waveforms having an odd multiple width of half the resonance period of the series resonance circuit 30.

Here, as shown in FIG. 2, the width of the generated output pulse command V may exceed three times the resonance period of the series resonant circuit 30. As described above, when the width of the output pulse of the inverter circuit 20 becomes long, the cycle of the inverter current flowing through the inverter circuit 20 changes, and as a result, switching is performed at a timing when the inverter current is not zero, and the switching loss increases. ..

Therefore, in the present embodiment, the gate signal generation unit 62 puts the inverter circuit 20 in the gate block state when the width of the output pulse command V exceeds three times the resonance period of the series resonance circuit 30. (The semiconductor switching elements 21 to 24 constituting the inverter circuit 20 are turned off). That is, as shown in FIG. 3, when the pulse width of the output pulse command V exceeds three times the resonance period of the series resonance circuit 30, the gate signal generation unit 62 has the resonance period of the series resonance circuit 30. The output pulse command V having a width three times as wide as half of the above is output, and thereafter, the output pulse command V is set to zero until the output pulse command V in the direction opposite to the current output pulse command V is output.

By putting the inverter circuit 20 in the gate block state, a current having a changed resonance frequency flows through the diode of the inverter circuit 20 due to the exciting inductance of the insulating transformer 40 in the light load state. When such a current flows, a voltage in a direction for suppressing the current is applied to the inverter circuit 20. As a result, as shown in FIG. 3, the output current I (inverter current flowing through the inverter circuit 20) of the inverter circuit 20 is suppressed, and the inverter current becomes zero at the switching timing according to the next output pulse command. Therefore, it is possible to prevent switching from being performed at a timing when the inverter current is not zero, and to suppress an increase in switching loss.

As described above, in the present embodiment, the control device 60 that controls the series resonance type power supply device 10 calculates the control amount for obtaining a desired output based on the feedback signal of the output voltage of the series resonance type power supply device 10. Based on the control amount calculated by the control amount calculation unit 61 and the control amount calculation unit 61, the output pulse command of the inverter circuit 20 is a combination of pulse waveforms having an odd multiple width of half the resonance period of the series resonance circuit 30. A gate signal generation unit 62 that generates gate signals for a plurality of switching elements 21 to 24 is provided so that an output pulse corresponding to the generated output pulse command is output from the inverter circuit 20. When the pulse width of the output pulse command exceeds three times the resonance period of the series resonance circuit 30, the gate signal generation unit 62 puts the inverter circuit 20 in the gate block state.

When the pulse width of the output pulse command exceeds three times the resonance period of the series resonance circuit 30 and the pulse width of the output pulse of the inverter circuit 200 becomes long, the inverter circuit 20 is put into the gate block state to form an insulated transformer. Due to the exciting inductance of 40, a current with a changed resonance frequency flows through the inverter circuit 20. When such a current flows, a voltage in a direction for suppressing the current flow is applied to the inverter circuit 20, and the current flowing through the inverter circuit 20 is suppressed, so that an increase in switching loss can be suppressed.

Although the present invention has been described with reference to the drawings and embodiments, it should be noted that those skilled in the art can easily make various modifications or modifications based on the present disclosure. Therefore, it should be noted that these modifications or modifications are within the scope of the present invention. For example, the functions included in each block and the like can be rearranged so as not to be logically inconsistent, and a plurality of blocks can be combined or divided into one.

10 Series resonance type power supply device 20 Inverter circuit 21 to 24 Semiconductor switching element 30 Series resonance circuit 31 Coil 32 Capacitor 40 Insulation transformer 50 Rectifier smoothing circuit 51 Bridge type full-wave rectifier circuit 52 Smoothing capacitor 60 Control device 61 Control amount calculation unit 62 Gate signal generator

Claims (2)

A control device that controls a series resonance type power supply device including an inverter circuit having a plurality of switching elements and a series resonance circuit connected to the inverter circuit.
A control amount calculation unit that calculates a control amount for obtaining a desired output based on a feedback signal of the output voltage of the series resonance type power supply device.
Based on the control amount calculated by the control amount calculating section, wherein the output pulse command of the inverter circuit forms the raw, as output pulses corresponding to the output pulse command thus generated is output from the inverter circuit, said plurality A gate signal generator that generates a gate signal for the switching element of
The gate signal generator
The buffer variable obtained by adding the control amount every half of the resonance period of the series resonance circuit is equal to or more than a predetermined value, and the pulse width of the output pulse command of the inverter circuit is half the period of the resonance cycle of the series resonance circuit. When it becomes an odd multiple of, the gate signal that inverts the output pulse of the inverter circuit is generated.
A control device characterized in that when the pulse width of the output pulse command exceeds three times the resonance period of the series resonance circuit, the inverter circuit is put into a gate block state. In the control device for controlling the description in claim 1.
When the pulse width of the output pulse command exceeds three times half of the resonance period of the series resonance circuit, the gate signal generation unit outputs an output pulse command in the opposite direction to the output pulse command until it outputs the output pulse command. A control device characterized in that the inverter circuit is in a gate block state.

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