CN1174543C - Phase Shift Control Bidirectional DC-DC Converter - Google Patents

Abstract

The phase-shift control bidirectional DC-DC converter of the present invention has two parts, a main circuit and a control circuit. The main circuit includes four switching tubes M ₁ -M ₄ , a clamp capacitor Cc1, two DC blocking capacitors Ct1, Ct2, a filter Inductor L _o and isolation transformer T, the control circuit includes a phase shift control chip, two PWM control chips connected to the output end of the phase shift control chip, the positive end of the error amplifier of each control chip is connected to the duty ratio control signal, and the output end is divided into two The output signal of the data selector is divided into two routes, one of which is input to the main circuit driver, and the other is input to the main circuit driver through the NOT gate, and the driving signal output by the driving circuit controls the main circuit driver. Circuit switch tube. On the basis of controlling the magnitude and direction of transmission power by phase shift, the present invention tracks and adjusts the PWM duty cycle according to the voltage amplitude on both sides, which can effectively reduce the current stress and current effective value of the converter, and the converter can realize Soft switching operation improves efficiency.

Description

Phase Shift Control Bidirectional DC-DC Converter

Technical field

The present invention relates to a phase-shift controlled bidirectional DC-DC converter.

Background technique

In order to reduce the volume and weight of the bidirectional DC-DC converter, the switching frequency must be increased. However, the increase of the switching frequency in the traditional converter will inevitably lead to the increase of the switching loss. Over the years, solutions to this problem have emerged. Some of them use resonance, quasi-resonance or multi-resonance technology, but the voltage and current stress of the converter is high, and frequency conversion control increases the difficulty of filter design; some add energy buffer absorption circuit or active clamping circuit, but increase the converter and control complexity; also some use full-bridge phase shift technology, this type of converter has a simple structure and few components, the disadvantage is that when the voltage on one side deviates from the balance value, the peak current and effective value of the converter will increase greatly, It is bound to increase the exchange of reactive power between input and output, thus increasing the current stress of power devices and magnetic components and increasing losses.

Contents of Invention

The object of the present invention is to provide a phase shift control bidirectional DC-DC converter with simple structure and capable of reducing the peak value and effective value of the current.

The phase-shift control bidirectional DC-DC converter of the present invention has two parts, a main circuit and a control circuit. The main circuit includes four switching tubes M ₁ -M ₄ , a clamp capacitor Cc1, two DC blocking capacitors Ct1, Ct2, a filter The inductance L ₀ and _the isolation transformer T, the primary side of the isolation transformer T is connected in series with the first DC blocking capacitor Ct1 and then connected across the two ends of one of the switch tubes M ₁ and M ₂ in series, the two switches The series circuit of the tubes M ₁ and M ₂ is connected in parallel with the DC power supply V ₁ , the secondary side of the isolation transformer T is connected in series with the second DC blocking capacitor Ct2, and then connected in parallel with the switch tube M ₄ , and respectively connected with the switch tube M ₃ and the clamping capacitor Cc1 The series circuit of the filter inductance L ₀ and the series circuit of the active load V ₂ are connected in parallel; the control circuit includes a phase-shift control chip whose two input terminals are respectively connected to a given power signal and a feedback power signal, and the output signal of the phase-shift control chip is divided into Two channels, respectively connected to the synchronization terminals of the first and second two PWM control chips, the positive terminal of the error amplifier of each PWM control chip is connected to the duty cycle control signal, and the output terminals are divided into two channels, respectively connected to the first and second The input terminal of the data selector, the common input terminal of the first and second two data selectors are respectively connected to the positive and negative control signals, the output signal of the data selector is divided into two routes, one of which is input to the main circuit driver, and the other is passed through The non-gate input main circuit driver, said main circuit driver includes a rising edge delay circuit, an isolation circuit and a driving circuit, the signal input to the main circuit driver is output to the isolation circuit through the rising edge delay circuit, and the output terminal of the isolation circuit is connected to the driver At the input end of the circuit, the driving signals output by the four driving circuits are respectively output to the switch tubes M ₁ -M ₄ of the main circuit.

The bidirectional DC-DC converter with phase shift control of the present invention can track and adjust the duty ratio of PWM according to the voltage amplitude on both sides on the basis of phase shift control of the magnitude and direction of transmission power, which can effectively reduce the current stress of the converter And the effective value of the current, and the converter can realize soft switching operation, which can improve the efficiency.

Description of drawings

Fig. 1 is main circuit of the present invention;

Fig. 2 is a control circuit block diagram of the present invention;

Fig. 3 is the circuit principle waveform of the present invention.

Detailed ways

The inventive phase-shift control bidirectional DC-DC converter has two parts, the main circuit and the control circuit. Referring to Figure 1, the main circuit includes four switching tubes M ₁ -M ₄ , clamping capacitor Cc1, DC blocking capacitors Ct1, Ct2, Filter inductance L ₀ and isolation transformer T, the switching tube can be a power field effect transistor, a power bipolar transistor or an insulated gate transistor or other controllable switching devices, the illustration uses a power field effect transistor, the original of the isolation transformer T The DC blocking capacitor Ct1 is connected in series and then connected across the two ends of one of the switch tubes M ₂ of the series switch tubes M ₁ and M ₂ , and the series circuit of the two switch tubes M ₁ and M ₂ is connected in parallel with the DC power supply V ₁ , _L1 in the figure is the leakage inductance of the isolation transformer. The secondary side of the isolation transformer T is connected in series with the DC blocking capacitor Ct2, and then connected in parallel with the series circuit of the switching tube _M4 , the switching tube _M3 and the clamping capacitor Cc1, and the series circuit of the filter inductance _L0 and the active load _V2 ; the control circuit As shown in Figure 2, it includes a phase-shift control chip 1 whose two input terminals are respectively connected to a given power signal A and a feedback power signal B. The output signal of the phase-shift control chip is divided into two paths, respectively connected to the first and second The synchronous terminals of the PWM control chips 2 are connected, and the positive terminals of the error amplifiers of each PWM control chip are connected to the duty ratio control signal D, where D=NV ₂ /V ₁ , where N is the number of turns of the transformer, and the output terminals are divided into two paths, respectively connected to the first One, the input terminal of the second data selector 3, the common input terminal of the first and second two data selectors are respectively connected to the positive and negative control signal E, the output signal of the data selector is divided into two routes, one of which is input to the main Circuit driver 8, another road is input main circuit driver 8 through NOT gate 4, and said main circuit driver 8 comprises rising edge delay circuit 5, isolation circuit 6 and driving circuit 7, and the signal of input main circuit driver is delayed through rising edge The circuit 5 is output to the isolation circuit 6, the output terminal of the isolation circuit is connected to the input terminal of the drive circuit 7, and the drive signals V _g1 , V _g2 , V _g3 , V _g4 output by the four-way drive circuit are respectively output to the main circuit switch tubes M ₁ ~ Gate of _M4 .

Here, the phase shift control chip can use UC3875, and the PWM control chip can use UC3525A.

Refer to Figure 3 for the working process of the converter. Figures (a) to (d) are the gate drive signals of the switching tubes M ₁ to M _4. Figure (e) is the voltage waveform between the contacts a and b of the main circuit. Figure ( f) is the voltage waveform between the main circuit c and d contacts, (g) is the voltage waveform of the converter leakage inductance _L1 , and (h) is the current waveform of _L1 .

During the operation of the converter, the switching frequencies of the four switching tubes _M1 , _M2 , _M3 and _M4 are the same, and the driving control of _M1 and _M3 maintains the same duty cycle D, and the driving control of _M2 and _M1 The drive control of _M4 and _M3 is complementary. By controlling the phase relationship of the driving signals of _M1 and _M3 , the magnitude and direction of energy transmission between the two DC sources _V1 and _V2 can be controlled. When the voltage of V ₁ or/and V ₂ deviates from the balance value, the time period when the switches _M1 and _M3 are turned on at the same time (Figure h, the time period t2~t3) and the time period when the switches _M2 and _M4 are turned on at the same time Time period (Figure h, t4 ~ t5 time period) the converter current remains unchanged, which can reduce the current stress, reduce the effective value of the current and the loss of the converter.

During the switching process of the switching tube M ₁ (or M ₃ ) and the switching tube M ₂ (or M ₄ ) on the same side of the transformer, due to the existence of the transformer leakage inductance L ₁ , after one of the switching tubes such as M ₁ is turned off, The current in the leakage inductance will discharge the equivalent capacitance connected in parallel to the two ends of the other switching tube _M2 on the same side, and then the latter _M2 will be turned on under the condition of zero voltage. In this way, the converter can realize soft switching operation in both directions. After any switching tube is turned off, the voltage at its two ends is clamped at a fixed voltage, and high voltage stress and oscillation will not occur.

Claims (1)

1. Phase-shift control bidirectional DC-DC converter, which is characterized by two parts: the main circuit and the control circuit. The main circuit includes four switching tubes (M ₁ ~ M ₄ ), clamping capacitor (Cc1), two DC blocking Capacitors (Ct1, Ct2), filter inductance (L ₀ ) and isolation transformer (T), the primary side of the isolation transformer (T) is connected in series with the first DC blocking capacitor (Ct1) and then connected across the first and second Both ends of one of the switch tubes (M ₁ , M ₂ ), the series circuit of the first and second switch tubes (M ₁ , M ₂ ) is connected in parallel with the DC power supply (V ₁ ), and the isolation transformer The secondary side of (T) is connected in series with the second DC blocking capacitor (Ct2) and connected in parallel with the fourth switching tube (M ₄ ), and is respectively connected with the series circuit of the third switching tube (M ₃ ) and the clamping capacitor (Cc1), The filter inductance (L ₀ ) is connected in parallel with the series circuit of the active load (V ₂ ); the control circuit includes a phase-shift control chip (1) whose two input terminals are respectively connected to a given power signal and a feedback power signal, and the phase-shift control chip The output signal is divided into two routes, which are respectively connected to the synchronous terminals of the first and second two PWM control chips (2), the positive terminal of the error amplifier of each PWM control chip is connected to the duty cycle control signal, and the output terminals are divided into two routes, respectively Connect the input terminals of the first and second data selectors (3), the common input terminals of the first and second two data selectors are respectively connected with forward and reverse control signals, and the output signals of the data selectors are divided into two paths, which One way is input to the main circuit driver (8), and the other is input to the main circuit driver (8) through the NOT gate (4). Said main circuit driver (8) includes a rising edge delay circuit (5), an isolation circuit (6) and The drive circuit (7), the signal input to the main circuit driver is output to the isolation circuit (6) through the rising edge delay circuit (5), the output terminal of the isolation circuit is connected to the input terminal of the drive circuit (7), and the output of the four-way drive circuit The driving signals are respectively output to the four switching tubes (M ₁ -M ₄ ) of the main circuit.

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