JPS63274372A - High-frequency resonance type converter using variable parameter circuit - Google Patents

Abstract

PURPOSE:To miniaturize an apparatus by fixing a switching frequency and regulating an output voltage through varying a resonance circuit parameter. CONSTITUTION:A resonance type DC constant-voltage power supply is composed of a DC power 1, a switch gear 2, a transformer 4, a rectifier 5 and a smoothing device 6 to supply the electric power to a load 7. In this case, there are also provided a variable parameter resonator 13 for a reactor L or capacitor C to be subjected to a variable control, a fixed frequency oscillation and drive unit 12, and a controller 14 for said resonator 13. Therefore, electric current and voltage can be controlled and a voltage regulation can be performed by the change of resonance conditions of said resonator 13, while a switching frequency remains as it is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION With the development of electronics technology, the demand for power supplies for electronic devices is increasing. In this case, with the application of LSI technology, the main body of electronic equipment has been miniaturized, functions have been consolidated, and prices have continued to decline. Under these circumstances, a highly efficient switching power supply is used for the power supply part, but it contains elements such as inductance and capacitance, and since large amounts of power are switched on and off using semiconductor switches, the heat generated by switching loss makes it difficult to apply integrated technology. There are problems with this, and miniaturization has been attempted mainly by increasing the switching frequency. As the switching frequency is increased, magnetic components such as transformer reactors and smoothing capacitors can be made smaller, but on the other hand, switching losses increase and cause heat generation. In order to reduce such switching losses, high-speed switching elements such as FETs are used, but as the switching speed increases, new problems such as generation of surge and noise occur. In order to solve this problem, a resonant circuit is used to make the current flowing through the switching element or the voltage applied to the switching element sinusoidal, and the voltage/current product when the switch is in the active state becomes zero, thereby eliminating switching loss. At the same time, attempts are being made to prevent the generation of noise. However, according to this method, it is necessary to change the switching frequency in order to adjust the output voltage, so it is necessary to design the magnetic elements and capacitors at the lowest frequency, and the effect of miniaturization is expected. I won't be able to do it.

The present invention aims to provide a means to solve this problem, and aims to fix the switching frequency and adjust the output voltage by changing the parameters of the resonant circuit, especially the capacitance of the resonant capacitor. There is.

FIG. 1 is a block diagram showing the principle of a conventional resonant DC constant voltage power supply. 1 is a DC power supply, 2 is a switch device, 3
is a resonant device consisting of a reactor and a capacitor, 4 is a transformer, 5 is a rectifier, 6 is a smoothing device, 7 is a load, 8 is an error amplifier, 9 is a reference voltage, 10 is a voltage frequency converter, and 11 is a switch drive circuit. ing. 2 and 3 show the current through an idealized switch and the voltage across the switch in order to understand the principle. FIG. 2 shows a current resonance type switch in which the current 1c passing through the switch becomes part of a sine wave due to the resonance device 3. On the other hand, the switch shown in FIG. 3 is of a voltage resonance type, in which the voltage Vc applied to the switch becomes part of a sine wave due to the resonance device 3.

As can be seen from FIGS. 2 and 3, switch loss Pc is the product of IC and Vc, so it can be seen that by making Ic or Vc part of the sine wave, Pc can be reduced to almost zero. In this case, in the current resonance shown in FIG. 2, the on-time is constant because the waveform of Ic is determined by the resonance conditions. On the other hand, in the voltage resonance type shown in FIG. 3, the voltage waveform is determined by the resonance conditions, so the off time is constant. Therefore, in order to control the voltage of the load 7, it is necessary to change the off time in FIG. 2 and the on time in FIG. 3, and both require a change in the switching frequency. The present invention is intended to solve this problem, and the fourth
The principle is shown in the figure. In FIG. 4, a variable parameter resonance device 13 is used instead of the resonance device 30 in FIG. 1, which can control the natural frequency of the resonance circuit by varying L or C. Instead, a fixed frequency oscillation drive 1112 is used. 14 is a control device for the variable parameter circuit. Therefore, by changing the resonance conditions, it is possible to control the current IC or voltage VC and adjust the voltage while keeping the switching frequency fixed. The most important thing in the new resonant converter shown in Fig. 4 is the resonant device using variable parameters shown in 13. In principle, it is only necessary to change C or C of the resonant circuit by an external signal. To do this, for example, there is a method of changing the capacitance by bias voltage using the nonlinear characteristics of a multilayer ceramic capacitor, and a method of changing the equivalent inductance by applying a bias magnetomotive force to a magnetic core with saturation characteristics. However, in order to significantly change the resonance characteristics, it is effective to couple an auxiliary switch to linear C or L, control its conduction time, and equivalently change C or L. FIGS. 5, 7, 9, and 11 show variable parameter circuits constructed in this manner. FIG. 5 is an example of a full waveform variable inductance circuit. FIG. 6 shows the principle waveform explaining the operation. In FIGS. 5 and 6, (a) is a,
(b) and (C
) are the principle waveforms showing the ON and OFF periods of the auxiliary switches 21 and 22, respectively, and (d) is the current waveform flowing from point a to point A. Auxiliary switch 21 and auxiliary switch 22
The drive signal of is synchronized with the voltage of terminals a and b, and the control angle α
, and both have opposite polarities. ωt=θl
Then, the switch 21 is turned on, and the switch 22 is given a turn-off signal. The voltage in the shaded area is applied to the axle 81, and the voltage in the old reactor is as shown in Figure 6(d).
A current as shown flows. This current is an integral of voltage and has a substantially sinusoidal waveform, and flows from point a through reactor 81, auxiliary switch 21, and diode 42 to point a. As shown in FIG. 6(d), the current becomes zero at ωt=02, and after that, in the 0th half cycle, which is stopped due to the diode 42, the auxiliary switch 21 and the auxiliary switch 22) diode 41 The same operation is repeated with the diode 42 replaced. The shaded part of the waveform in FIG. 6(a) is the voltage applied to the axle 81,
Other parts are auxiliary switch 21, 22 and diode 4
142. As shown in FIG. 6, since the current passing through the auxiliary switch and the voltage applied to the auxiliary switch are not the same, it can be seen that there is no switching loss in the auxiliary switch.

In addition, in Fig. 6, the current waveform in (d) is
Expanding it in a series and considering only the fundamental wave component, the current waveform in (d) lags the voltage waveform in (a) by 90'', has the characteristics of the circuit beam in Figure 6, and its equivalent inductance is given by the following formula: I understand that it can be expressed.

Leq=L/(2-[2α-5in(2a)]/7Y
) (1) However, it is also the inductance of the axle 81.

As shown in equation (1), the equivalent inductance of the circuit shown in FIG. 5 is a function of the control angle α, and can be changed by controlling the control angle α, that is, the conduction period of the auxiliary switch.

FIG. 7 shows the configuration of a full-wave variable capacitance circuit, and FIG. 8 shows its principle operating waveforms. In Figures 7 and 8, (a) is the sine wave current flowing from point a to point a, and (b) and (C) are the on and off states of the auxiliary switches 23 and 24, respectively. The principle waveform showing the period, (d) is the voltage waveform at both ends of 8%. The shaded current in (a) is the current flowing through the capacitor 91, and the others are the current flowing through the auxiliary switch 23, 24 and diode 4.
It flows on 3.44. Therefore, as in FIGS. 5 and 6, since the current and voltage do not overlap, it can be seen that there is no switching loss, and the equivalent capacitance of the circuit in FIG. 7 due to only the fundamental wave component can be obtained as shown in the following equation.

Ceq=C/(2-[2a-5in(2a)co/π) (2) where C is the capacitance of the capacitor 91.

9 and 10 are half-wave variable inductance circuits and operating waveforms showing the principle thereof. In Figures 9 and 10,
(a) shows the sine wave voltage applied to terminals a and b, and the parts without diagonal lines are the auxiliary switch 25 and diode 45.
(b) is a waveform showing the on/off period of the auxiliary switch 25, and (C) is a waveform of the current flowing from point a to point A.

Figures 11 and 12 show a half-wave variable capacitance circuit and its principle operating waveforms. In Figures 11 and 12, (a) shows a sine wave current flowing from point a to point The portion without is the current flowing through the switch 26 and the diode 46, (b) is a waveform showing the on and off periods of the auxiliary switch 26, and (c) is the voltage waveform at both ends of a and 5.

Similarly, it can be seen that the circuits of FIGS. 9 and 11 also have no switching loss, and the equivalent parameters can be varied with the control angle α. Among the variable parameter circuits described above, the variation range of the control angle α of the full-wave circuit is from π/2 to π, while the variation range of the control angle α of the half-wave circuit is from O to π.

In a conventional high-frequency resonant converter, if the variable inductance circuit is connected in parallel where continuous AC voltage appears, or the variable capacitance circuit is connected in series where AC current flows continuously. , it becomes possible to control the equivalent inductance or equivalent capacitance with the control angle α, and the output can be adjusted by changing the natural frequency of the resonant converter. However, AC voltage and AC current are not necessarily sine waves.

(First Embodiment) FIG. 13 shows a first embodiment of the present invention in which voltage adjustment is performed for a series resonant DC-DCC set using a full-wave variable inductance circuit. Bipolar transistors are used as switching elements. Reactor 84, transistor 33 used as an auxiliary switch
and 34 and diodes 49 and 50 constitute a full-wave variable inductance circuit. The voltage detector 16 detects the phase of the voltage of the resonant capacitor 95 and sends a synchronizing signal to the control device E.
Give to 14. The control device 14 compares and amplifies the output voltage of the load 7 and the reference voltage 9, changes the resonance frequency through the control angle α of the full-wave variable inductance circuit, and controls the output voltage. FIG. 14 is an example of the experimental results shown in FIG. 13. FIG. 15 shows the case where voltage adjustment is not performed, and this clearly demonstrates the effectiveness of the present invention.

(Second Embodiment) FIG. 16 shows a class E resonant DC-DC converter using a half-wave variable capacitance circuit, which is another embodiment of the present invention. A MOSFET is used as a switch element. In this case, the MO9FET's built-in diode can also be used. Auxiliary switch 72 by MOSFET) Built-in diode 56 and capacitor 100 constitute a half-wave variable capacitance circuit. The current detector 17 detects the phase of the current of the resonant axle 86, uses it as a synchronization signal, and supplies it to the control device 14. The control device 14 controls the output voltage of the load 7 and the reference voltage 9.
is compared and amplified, and the natural oscillation frequency of the resonant circuit is changed through the control angle of the half-wave variable capacitance circuit to control the output voltage. 171st! I is an example of the experimental results shown in FIG. 16, and the switching frequency in this case is IMHz. FIG. 18 shows a case where voltage adjustment is not performed, and the effectiveness of the present invention can be confirmed from this. Fig. 17 also shows the efficiency, and it can be seen that a high efficiency of 93% can be obtained.

As can be seen from the above explanation, it has become clear that by using a variable parameter circuit, it is possible to adjust the voltage of a high frequency resonant converter, and thereby a compact, lightweight, and highly efficient power supply device can be obtained.

[Brief explanation of the drawings] Figure 1 is a block diagram of a conventional resonant DC-DCC set, Figures 2 and 3 are idealized current and voltage waveforms, and Figure 4 is a variable parameter circuit. Resonant type DC used
-DCC complete set-A block diagram, Fig. 6 is a block diagram of a full-wave variable inductance circuit, Fig. 6 is a principle operating waveform of a full-wave variable inductance circuit, Fig. 7 is a block diagram of a full-wave variable capacitance circuit, and Fig. 6 is a block diagram of a full-wave variable inductance circuit. Figure 8 shows the principle operation waveform of a full-wave variable capacitance circuit, Figure 9 shows the configuration diagram of a half-wave variable inductance circuit, and Figure 10
The figure shows the principle operation waveform of a half-wave variable inductance circuit, the first
Figure 1 is a configuration diagram of a half-wave variable capacitance circuit, Figure 12 is the principle operating waveform of a half-wave variable capacitance circuit, and Figure 13 is the configuration of a series resonant DC-DCC regulator regulator using a full-wave variable inductance circuit. Figures 14 and 15 are examples of the experimental results shown in Figure 13, Figure 16 is a block diagram of a class E resonant DC-DC converter using a half-wave variable capacitance circuit, and Figures 17 and 18 are FIG. 16 is an example of the experimental results. 1-m--DC power supply, 2--switch device, 3-m--acdle and capacitor together wRiIi1, 4--h
Lance, 5--! I flow device, 6---Smoothing device, 7.-
Load, 8--error intensifier, 9-m-reference voltage, IO-
・-voltage frequency converter, 11-m-drive device, 12-11 fixed frequency generator S drive device・13-m-resonant device using variable parameter circuit, 14-11 iaj device, 15
-m- phase detector, 16-- voltage detector, 17--
-Current detector, 21~26---Switch/31~3
4---Bipolar transistor switch・41~5
4-m-diode, 55-56---M OS F
E T built-in diode, 71~72---M OS F
ET switch, 81~86°-reactor, 91~
100-m-capacitor Fig. 1 Fig. 2 Fig. 3 I-in 1 414 1'+['A 71-1 Fig. 9 Fig. 10 Fig. 11 Fig. 12 11 ril engineering 1 charge current (to) -→ 16th [4 00, 51, 01, 52, 02, 5 negative C night -B (≦ε (A) --・th]
7 Figure 0 0.5 1,0 1.5 2.0 2.5 Load current (A) -→ Figure 18

Claims (2)

[Claims] (1) In a resonant converter that uses a resonant circuit to make the voltage applied to the switch or the waveform of the current passing through the switch almost a sine wave, thereby reducing the loss accompanying the opening and closing of the switch, A high-frequency resonant converter that uses a variable parameter circuit that adjusts the output voltage by controlling the frequency of vibration. (2) In claim (1), as a means for controlling the natural frequency of the resonant circuit, an auxiliary switch is coupled to the capacitor or reactor of the resonant circuit, and the conduction time of the auxiliary switch is varied. A high frequency resonant converter using a variable parameter circuit that controls the equivalent capacitance of the reactor or the equivalent induction coefficient of the reactor.