JPH01186169A - Driving gear for resonance type load - Google Patents

Abstract

PURPOSE:To save power, to miniaturize a driving gear and to reduce the cost required, by ON/OFF controlling the output of a rectification means with a switch through a transformer. CONSTITUTION:A driving gear is equipped with an LPF, a rectifier D1, a resistance 17, a capacitor C, a control amplifier 4, a multiplier 5, a comparator 6, a gate control circuit 7 and a start circuit 8. A choke coil on a smoothing filter side and a transformer on a resonance type load circuit 10 side are put to use in common, unifying an FET 11 for switching. For a transformer T11 used in common of this communal use section 12 the primary winding is formed by two parts of n11-n12, the output voltage of which is inputted into the gate control circuit 7. Two power consumption circuits can thereby be unified and power saving, miniaturization, etc., can be implemented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a driving device for a resonant load.

[Conventional technology 1] For example, an active smoothing filter in a power supply device can achieve 1 by making a rectified current waveform similar to a voltage waveform.
This is to prevent noise from being generated on the next side due to sudden changes in current.

FIG. 2 shows a resonant load driving device as an application example of a conventional power supply device using an active smoothing filter. The active smoothing filter in this drive device basically consists of a DC-DC converter (step-up type). As shown in Figure 2, a commercial frequency rated voltage power supply is connected to the input terminals IA and IB, and the + (plus) output terminal of the bridge rectifier D1 is connected to the input terminals via a low-pass filter LPF. An output Vl is obtained.

One end of the choke coil Ll is connected to the middle output end of the rectifier (diode) Dl, the anode of the diode (flywheel diode) C2 is connected to the other end of the coil LL, and the output from the cathode of the diode D2 is It is guided to a resonant load circuit 10. C2 is the same diode D2
is a smoothing capacitor connected to the cathode of

Resistors R1 and R2 connected in series are connected between the output terminal of the rectifier DI and ground, and a capacitor CI is also connected. A series circuit of an FET (field effect transistor) 3 (its source and drain) and a resistor R3 is connected between the other end of the choke coil L1 and ground. A detection winding L2 for current detection is wound around the choke coil L1. The output end voltage of the detection winding L2 is at a high (H) level while the choke coil Ll is discharging the stored energy.

Reference numeral 4 denotes a control amplifier consisting of a differential amplifier, with a reference voltage at its non-inverting input terminal and resistors R4 and R at its inverting input terminal.
The output side voltage of diode 2 divided by 5 and 5 is applied to resistor R7.
A direct current (Tic) output for determining the magnitude of the target value is obtained at the output end. Note that the output of the control amplifier 4 is fed back to the inverting input terminal via the capacitor C4 and resistors R8 and R9. As a result, the control amplifier 4
has high gain for direct current and low gain for alternating current.

5 is a multiplier, and one input terminal receives the output of the control amplifier 4, and the other input terminal receives, as an input voltage, a voltage obtained by dividing the rectified output Vl of the rectifier D1 by resistors R1 and R2. Then, by multiplying these, a threshold value (target value) is obtained as an output.

6 is a comparator consisting of a differential amplifier, and the output of the multiplier 5 is input to the non-inverting input terminal, and the voltage from the shunt resistor R3 for detecting the current flowing through the FET 3 is input to the inverting input terminal.

The voltage drop detected by the shunt resistor R3 when the FET3 is conductive corresponds to the instantaneous value of the current flowing through the coil Ll.

The output of the comparator 6 is the voltage value of the shunt resistor R3.
When the output value (i.e. target value) is reached, it turns off (Lo)
7 is a gate control circuit which manually inputs the output of the comparator 6 and turns off the gate of the FET 3 when the output is turned off. Then, the gate control circuit 7 connects the detection winding L2
When the choke coil L1 finishes discharging and the output voltage of the detection winding L2 becomes zero, the gate of the FET 3 is turned on.

Note that 8 is a start circuit that generates information for the start operation when starting this device, and is connected to resistors R8 and RI.
O, capacitor C6, diode D3. D4, the output voltage of the rectifier DI generated immediately after power-on is applied via a resistor R6, and then this voltage is transferred via a diode p3 to the anode of the diode D2, and to the anode of the diode D4. Gate control circuit 7 via resistor RIO
The starting information will be provided by each person.

According to the above configuration, during the conduction period of FET3, the choke coil LL flows current while accumulating magnetic energy, and when this current reaches a peak value (target value), FET3
is turned off, coil Ll starts discharging while passing current, and at the end of discharging, the output end voltage of detection winding L2 becomes zero, FET3 is turned off, and choke coil L
l begins to flow current while accumulating magnetic energy again. By operating in this way, the average value of the current iL flowing through the choke coil Ll is increased as shown in FIG.
can be changed in response to the waveform of the voltage Vl that changes at the commercial frequency. Since the current flowing through the choke coil Ll has a relatively high frequency, its influence is removed by the low-pass filter LPF, and noise etc. do not leak to the primary side.

Next, the operation of the resonant load circuit IO will be explained. This circuit IO drives a load (for example, a high-voltage neon tube) TB, and first, the primary winding (T
A current 11 begins to flow through I.nl). This 11 is T1・
The capacitor C3 is charged via nl. At this time, the energy induced in the secondary winding (TI/R2) of the transformer T1 is transferred to the primary winding (T2/nl) of another transformer T2.
), then through capacitors C9 and C8 to T1.
During this time, energy is induced in the secondary winding (T2/R2) of the transformer T2, and the generated voltage is applied to the gate of the FET 9 via the resistor RIG. Then, FET9 is turned on, more energy is induced in Tl-R2, and voltage continues to be applied to the gate of FET9 in the same manner as described above.

Next, when a predetermined amount of energy is accumulated in T1・nl, I
The increase in t stops, energy is no longer induced in Tl-R2 from the T1/nl side, and the gate of FET9 is turned off. Then, the energy stored in T1·nl is transferred to the internal diode D5 of FET9. Tl-nl
, is discharged via capacitor C2, and at the same time, energy is generated in T1 and R2 in the opposite direction to T2 and R2.
Energy in the opposite direction is also induced, and a current flows from the Zener diode ZDI toward the resistor RIO. Therefore, FET9 remains off.

Also, the capacitor C3 has an initial charge of FE.
This operation repeats the cycle of discharging when T9 turns on, then charging while FET9 is off, and discharging just before FET9 turns on.
smooth the current flowing through the

By repeating the above operation, an oscillation operation is achieved, and when this oscillation starts, current also flows to the load TB.

[Problems to be Solved by the Invention] However, in power equipment that requires a high input power factor as described above, an active smoothing filter and a resonant load circuit for improving the power factor must each have independent power consumption circuits. exists. Moreover, the power capacities required for the two power consuming circuits are equal. Therefore, the power consumption of the device as a whole is large and the number of parts is large, which is disadvantageous to miniaturization of the device, and furthermore, the cost is high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a resonant load driving device that can solve the above-mentioned problems and can reduce power consumption, size, and cost.

[Means for Solving the Problems 1] The present invention comprises a rectifying means for rectifying an alternating current signal from an alternating current power supply, a transformer having one end of a primary winding connected to an output end of the rectifying means, and a secondary winding of the transformer. A resonant load connected to the line, a switch that turns on and off continuity between the other end of the primary winding of the transformer and ground, and a switch that turns on and off based on the rectified output signal from the rectifier and the signal flowing to the switch. and means for controlling.

[Function] According to the present invention, two power consuming circuits that drive a resonant load can be combined into one, thereby achieving power saving, miniaturization, and cost reduction.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and the same parts as in FIG. 2 are given the same reference numerals. The features of this embodiment are as follows:
The choke coil on the smoothing filter side and the transformer on the resonant load circuit side are shared, and only one FET is used for switching. This shared portion 12 is shown by a dotted line.

As shown in Figure 1, LPF, rectifier Di, resistor 11
1, R2, R7, 118, R9, :y Densor C1,
C4, control amplifier 4, multiplier 5. Comparator 6. Gate control circuit 7. The start circuit 8 has the same configuration as in FIG. 1, except that the destination of the output of the diode D3 of the start circuit 8 is different.

Next, the common part 12 will be explained. Tll is a shared transformer, and the primary winding is divided into two parts (ntt.

n12), one portion nil corresponds to the secondary winding n21 connected to the load TB, and the other portion n12 corresponds to the detection winding n22. This detection winding n22 is T
The current flowing through the primary winding of ll is detected, and the voltage from its output terminal is input to the gate control circuit 7. One end of the primary winding of the shared transformer Tll is connected to the output end of the rectifier DI, and the other end is connected to the drain of the shared FET II. The source of FETII is grounded via a shunt resistor R3. The voltage of the shunt resistor R3 is input to the comparator 6 along with the output of the multiplier 5. Also, FETII
A capacitor C2 and a cathode of a diode D3 of the start circuit 8 are connected to the drain of the start circuit 8.

The secondary winding n21 of the shared transformer Tll has a load TB.
A capacitor (:8.C9) in series is connected in parallel, and a coil L3 is further connected in series.The current flowing through the secondary winding n21 is detected by the current transformer CT, and the detected current is connected to the diode Dll. After being rectified by and smoothed by capacitor C1l, the resistor R
7 to the inverting input terminal of the control amplifier 4.

Next, the operation of this embodiment will be explained.

When the power is turned on, the current appearing at the output terminal of the rectifier D1 quickly reaches its peak, and in the process the current that appears at the output terminal of the rectifier D1 quickly reaches the peak, and the current flows through the resistor R6 and diode D3 of the start circuit 8 to the drain of the FET 11, and the resistor R6, the diode D4, and the resistor RIG.
, and input signals of the same phase to the gates of FET II via the gate control circuit 7. This causes the primary winding of the shared transformer Tll, FETII.

Control amplifier 40 Multiplier 5. Comparator 6. Gate control circuit 7
starts operating as an active smoothing filter (similar to FIG. 1).

That is, the output (Vl) of the rectifier DI is charged into the capacitor C2 via the primary winding (Tll-nll+n12) of the shared transformer T11. At this time, the detection winding n2
Energy is induced in FET II, and its output terminal voltage v3 is input to the gate control circuit 7, which turns on the gate of FET II. As a result, when FET II is turned on and a predetermined amount of energy is stored in the primary winding of the shared transformer Tll, the output terminal voltage v3 of the detection winding n22 is reversed, and the gate control circuit 7 turns on the gate of the FET11. control, and the FET II is turned off.

Then, the energy stored in the primary winding of the shared transformer Tll is released via the resistor R3, the internal diode D5 of FETII, the primary winding (nll+n12), and the capacitor CI.

When FETII is off, the energy stored in the primary winding of the shared transformer Tll is released, and the capacitor C2
After charging is completed, the capacitor C2 is connected to the common transformer Tll.
primary winding, capacitor CI, resistor R3 and FET
The output (Vl) of the rectifier Di starts to be charged again via the primary winding of the shared transformer Tll. At the same time as this recharging, energy is induced in the detection winding n22, and the FET is
II is turned on, and the energy due to the output (vl) from the rectifier p1 is increasingly accumulated in the primary winding of the shared transformer Tll.

By repeating the above steps, that is, by oscillating, the shared transformer Tl
A current alternately flows through the winding n21 of the coil L3. Load TB is driven by a resonant circuit of capacitors C8 and C9.

[Effect of the Invention 1] As explained above, according to the present invention, two power consuming circuits can be combined into one, resulting in power saving.

It is possible to provide a resonant load drive device that can be made smaller and lower in cost.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram of a conventional resonant load driving device, and Fig. 3 is a diagram showing the relationship between switching waveform and rectified voltage at choke coil output. .

Claims (1)

[Claims] 1) A rectifier for rectifying an AC signal from an AC power supply, a transformer having one end of a primary winding connected to the output end of the rectifier, and a secondary winding of the transformer. a connected resonant load; a switch that turns on/off continuity between the other end of the primary winding of the transformer and ground; and a switch that operates the switch based on a rectified output signal from the rectifier and a signal flowing to the switch. What is claimed is: 1. A resonant load drive device, comprising means for on/off control.