TWI458236B - Single-input multiple-output dc/dc converter - Google Patents

Description

Single Input Multiple Output DC/DC Converter

The present invention relates to a DC/DC conversion circuit, and more particularly to a single input multiple output DC/DC conversion circuit.

In recent years, due to the global concern about the energy crisis and carbon dioxide emissions, many countries are constantly looking for new alternatives to green energy, in the face of today's increasingly stringent emissions control, oil depletion and global greenhouse gas emissions Under the catastrophe of warming, the automotive industry and governments have invested in the development of fuel cell power technology with clean effects, hoping to replace the traditional internal combustion engine.

Therefore, if you want to use the fuel cell as the power of the motor of a mobile vehicle (such as an electric vehicle), you need to use a balance of plant (BOP) to monitor the fuel cell voltage and temperature to determine whether to start. Or stop the fuel cell system. When the operating temperature of the fuel cell is too high, the water-cooling system and the fan of the peripheral device of the fuel cell are turned on, so that the fuel cell does not forcibly shut down the system due to excessive temperature.

Traditionally, in order to maintain the proper operation of the balance control system and fuel cell peripherals, auxiliary batteries (such as general batteries or batteries) are used on the fuel cell power supply system to provide operating voltage levels for the balance control system and fuel cell peripherals. quasi. In addition, the initial startup of the fuel cell power system also requires an auxiliary battery to drive to generate an operating voltage level sufficient to drive the mobile carrier.

However, in the design of the traditional fuel cell power supply system, the reuse of the auxiliary battery is not taken into consideration, so that when the auxiliary battery is exhausted, the balance control system and the fuel cell peripheral device are maintained without the auxiliary battery. In the case of operating voltage, the fuel cell power supply system is unstable, resulting in forced shutdown or damage. Therefore, when the auxiliary battery is exhausted, it is necessary to replace the new auxiliary battery or the original auxiliary battery for offline charging operation to operate the fuel cell power supply system normally, but this will cause the fuel cell power supply system to be used. Inconvenient.

In addition to fuel cell applications, other renewable energy sources (such as solar photovoltaic systems) also have multiple sets of voltage level output requirements, because the general circuit control board or peripheral accessory system needs to be activated to modulate the power output before the energy supply is stable. Therefore, single-input multi-output DC/DC conversion circuits are one of the indispensable devices.

The embodiment of the invention provides a single-input multi-output DC/DC converter, so that the auxiliary battery can be a battery with repeated charge and discharge capability, and the single-input multi-output DC/DC converter requires only one switch, that is, can output Multiple different voltage levels. In this way, the fuel cell power supply system can simultaneously charge the auxiliary battery when driving the motor of the mobile vehicle, and the use of the auxiliary battery is further extended, in addition to the inconvenience of requiring frequent replacement of the auxiliary battery or offline charging. The cycle, in turn, reduces the cost of using and manufacturing the fuel cell power system.

Embodiments of the present invention provide a single input multiple output DC/DC converter, and the single input multiple output DC/DC converter includes a low voltage circuit, an auxiliary circuit, a medium voltage circuit, and a high voltage circuit, and the low voltage circuit is coupled to the auxiliary circuit, and The low voltage circuit is coupled to the high voltage circuit through the medium voltage circuit. The low voltage circuit has a primary side winding and a switching element. The switching element is coupled between the primary side winding and the ground end and is controlled to be turned on by the control signal. When the switching element is turned on, the primary side winding stores energy in the first magnetic field. When the switching element is turned off, the primary side winding releases the energy stored in the first magnetic field. The auxiliary inductor in the auxiliary circuit stores the energy released by the primary winding when the switching element is turned off, and outputs the first output voltage according to the energy released by the primary winding and the auxiliary inductor. The medium voltage circuit has a secondary side winding and a medium voltage capacitor, and the secondary side winding generates a potential difference through mutual inductance with the primary side winding. When the switching element is turned on, the secondary winding stores a potential difference from the medium voltage capacitor. When the switching element is turned off, the secondary side winding has a freewheeling potential difference to the medium voltage capacitor. The high voltage circuit is configured to receive energy in the medium voltage capacitor to output a second output voltage.

In the embodiment of the present invention, the single-input multi-output DC/DC converter further includes a clamp circuit, and the clamp circuit is coupled between the low voltage circuit and the medium voltage circuit. The clamp circuit has a clamp capacitor. The clamp capacitor is used to store the leakage inductance energy of the primary winding when the switching element is instantaneously turned off, and releases the stored energy to the intermediate voltage circuit after the leakage current of the primary winding is freewheeled.

In summary, the embodiment of the present invention provides a single-input multi-output DC/DC converter, which has a single-input multi-output DC/DC converter through the setting of an auxiliary circuit and a clamp circuit, and the leakage inductance characteristic of the coupled inductor. Low step-up ratio output voltage source with high step-up ratio output voltage source. In addition, the leakage inductance of the coupled inductor enables the switching element to achieve zero current switching, thereby reducing switching losses and reducing the reverse recovery current of the diode to reduce electromagnetic interference in the circuit. In addition, the single-input multi-output DC/DC converter of the embodiment of the present invention only needs to use one set of switching elements, so that the single-input multi-output DC/DC converter can output multiple sets of voltage sources with different voltage levels, which not only reduces the voltage source. The cost of circuit design increases the practicality of practical applications. The single-input multi-output DC/DC converters described in the general literature are mostly applied to the mains rectification to supply different levels of DC voltage for use in the control board chip, which belongs to the step-down DC converter, and the DC conversion developed by the present invention The device is a booster type and is particularly suitable for use in low-voltage renewable energy generation.

The detailed description of the present invention and the accompanying drawings are to be understood by the claims The scope is subject to any restrictions.

[Example of Single Input Multiple Output DC/DC Converter]

Please refer to FIG. 1. FIG. 1 is a functional block diagram of a single input multi-output DC/DC converter according to an embodiment of the present invention. As shown in FIG. 1, the single-input multiple-output DC/DC converter 10 includes a low voltage circuit 100, a control circuit 101, an auxiliary circuit 102, a clamp circuit 104, a medium voltage circuit 106, and a high voltage circuit 108. The low voltage circuit 100 is coupled to the control circuit 101, the auxiliary circuit 102, and the clamp circuit 104. The clamp circuit 104 is coupled to one end of the medium voltage circuit 106, and the other end of the medium voltage circuit 106 is coupled. High voltage circuit 108.

Therefore, the single-input multi-output DC/DC converter 10 can be mainly divided into two block circuits, which are respectively the first circuit 11 composed of the low-voltage circuit 100, the control circuit 101, and the auxiliary circuit 102, and are controlled by the low-voltage circuit 100. The circuit 101, the clamp circuit 104, the intermediate voltage circuit 106, and the second circuit 12 of the high voltage circuit 108. The components of the single-input multi-output DC/DC converter 10 will be described in detail below.

Please refer to FIG. 2. FIG. 2 is a schematic circuit diagram of a single input multi-output DC/DC converter according to an embodiment of the present invention. The low voltage circuit 100 includes a DC input power source V _FC , a primary side winding L _P , and a switching element S ₁ . The DC input power source V _{FC is} used to provide an input voltage source of the single-input multi-output DC/DC converter 10. Therefore, the low-voltage circuit 100 is a common circuit of the first circuit 11 and the second circuit 12 for the purpose of single input and multiple output.

The primary winding L _P is a conductor (also referred to as a coupled inductor) of a transformer having a high excitation current, and the first end of the primary winding L _P is coupled to the anode terminal of the DC input power source V _FC , and the primary side The second end of the winding L _P is coupled to the switching element S ₁ . In general, the primary side winding L _P generates a first magnetic field due to a change in current passing, and generates a first electromotive force due to electromagnetic induction while storing the first electromotive force in the first magnetic field in the form of energy. According to the change in resistance to current.

The switching element S ₁ has three ends of a first end, a second end and a control end, the first end of the switching element S ₁ is coupled to the second end of the primary side winding L _P , and the second end of the switching element S ₁ is coupled Connected to the ground terminal, and the control terminal of the switching element S ₁ is coupled to the control circuit 101. The switching element S _{1 is} controlled by a control signal generated by the control circuit 101, and turns on the switching element S ₁ by a control signal. In other words, the control circuit 101 through the generated control signal to control the duty cycle of the switching element S ₁ (duty cycle). In practice, the switching element S ₁ is a gold-oxygen half field effect transistor (MOSFET) that is anti-parallel diode, and the control signal is the gate signal of the gold-oxygen half field effect transistor of the anti-parallel diode.

In practical example, when the switching element S _{1 of the} low voltage circuit 100 receives the control signal from the control circuit 101 and is turned on, that is, the conduction of the switching element S ₁ provides the current of the primary side winding L _P connected to the ground terminal. The path causes the current of the DC input power source V _{FC to} flow through the primary side winding L _P to induce electromagnetic induction to generate a first electromotive force, and store the first electromotive force in the form of energy in the first magnetic field of the primary side winding L _P . When the switching element S ₁ is turned off, the first magnetic field of the primary side winding L _P releases the stored energy to resist the change in current. In addition, the _VFC terminal of the DC input power supply of the low voltage circuit 100 can be further connected with a filter capacitor C _FC to filter out the noise of the DC input power source V _FC , so that the DC voltage outputted by the low voltage circuit 100 is more stable and smooth, but The invention is not limited here to whether it is necessary to use a filter capacitor C _FC .

The auxiliary circuit 102 includes an auxiliary inductor L _aux , a diode D ₁ (first diode), a filter capacitor C _{O1 ,} and a first output load R _O1 . The first end of the auxiliary inductor L _aux is coupled to the junction of the second end of the primary winding L _{P and} the first end of the switching element S _{1 , and the} second end of the auxiliary inductor L _aux is coupled to the diode D ₁ Anode end. The cathode end of the diode D ₁ is coupled to the parallel filter capacitor C _O1 and the first output load R _O1 .

The auxiliary inductance L _{aux is} used to temporarily store the energy released by the first magnetic field. When the auxiliary inductance L _aux between the first voltage across the output load R _O1 is greater than the diode D ₁ ON voltage, the forward conducting diode D _1, according to output a first output to a first current i _O1 The output load R _O1 (for example, a battery) is such that the first output load R _O1 carries the first output voltage V _O1 ; the voltage across the auxiliary inductor L _aux and the first output load R _O1 is less than the conduction of the diode D ₁ At voltage, the diode D ₁ is turned off, causing the first output current i _{O1 to} transition to zero. In addition, the filter capacitor C _{O1 is} used to provide a relatively stable voltage source of the first output load R _O1 .

In a practical example, when the switching element S ₁ is turned off, the low voltage circuit 100 and the auxiliary circuit 102 form a closed loop, so that the primary winding L _P starts to release the energy originally stored in the first magnetic field. Part of the energy released is temporarily stored in the auxiliary inductor L _aux , and the remaining energy is outputted by the diode D ₁ , thereby outputting the first output voltage V _O1 , and using the first output voltage V _O1 to the battery Charge it. When the switching element S ₁ is turned on, so that the primary winding L _P begins to store energy in the first magnetic field, and the auxiliary inductance L _aux in order to resist change in current will begin to release energy remaining in the auxiliary inductance L _aux temporarily stored, and through The turned-on diode D ₁ outputs a first output voltage V _O1 to charge the battery. In addition, after the auxiliary inductor L _aux releases energy, the auxiliary circuit 102 stops the entire operation until the switching element S ₁ is turned off next time.

The clamping circuit 104 includes a clamping capacitor C ₁ and a diode D ₂ (second diode). The anode ends of the clamp capacitor C ₁ and the diode D ₂ are respectively coupled to the first end and the second end of the primary side winding L _P , and the cathode end of the diode D ₂ is connected to the other end of the clamp capacitor C ₁ . The medium voltage circuit 106 is coupled. The clamp capacitor C _{1 is} used to store the leakage inductance energy of the primary side winding L _P at the moment when the switching element S _{1 is} turned off to avoid damage of the switching element S ₁ .

In an actual operation example, when the switching element S _{1 is} turned off, the leakage inductance energy of the primary side winding L _P needs to be freewheeled, and the primary side winding L _P is made by the forward conduction of the diode D ₂ . The leakage inductance energy can be stored to the clamp capacitor C ₁ . After the leakage current of the primary side winding L _P is freewheeled, the diode D ₂ is reversely turned off, so that the clamped capacitor C ₁ releases the stored energy to the intermediate voltage circuit 106.

The medium voltage circuit 106 includes a secondary side winding L _S , a medium voltage capacitor C _{2 ,} and a diode D ₃ (third diode). The secondary winding L _S is another conductor (also referred to as a coupled inductor) of the transformer with high excitation current, and the first end of the secondary winding L _S is coupled to the cathode end and the diode of the diode D ₂ The junction of the anode end of the body D ₃ and the second end of the secondary winding L _S are coupled to one end of the medium voltage capacitor C ₂ . The other end of the medium voltage capacitor C ₂ is coupled to the junction of the cathode end of the diode D ₃ and the high voltage circuit 108.

The secondary side winding L _{S is} transmitted through mutual inductance with the primary side winding L _P to generate a second electromotive force and an induced current. Further, the second electromotive force is proportional to the secondary winding L _S and the primary winding turns ratio of the primary winding L _P, i.e. when the ratio of the larger number of turns of winding and the secondary winding L _S L _P of the primary winding, which The larger the second electromotive force generated by the mutual inductance, the higher the voltage level v _LS across the secondary side winding L _S .

In a practical example, when the switching element S _{1 is} turned on, the secondary winding L _S generates a second electromotive force due to mutual inductance with the primary side winding L _P , and transmits the diode D ₃ through the forward conduction diode. The piezoelectric capacitor C ₂ can store the energy of the secondary winding L _S ; when the switching element S ₁ is turned off, the secondary winding L _S needs to release the remaining leakage inductance energy to the medium voltage capacitor C ₂ , so the diode D ₃ will continue to conduct continuously until the remaining secondary side leakage energy continues to flow, and the diode D ₃ is reversed.

The high voltage circuit 108 includes a diode D ₄ (fourth diode), a filter capacitor C _{O2 ,} and a second output load R _O2 . The anode end of the diode D ₄ of the high voltage circuit 108 is coupled to the junction of the cathode end of the diode D ₃ and the medium voltage capacitor C ₂ , and the cathode ends of the diode D ₄ are respectively coupled in parallel. Filter capacitor C _O2 and second output load R _O2 .

The high voltage circuit 108 is configured to receive the electrical energy released by the medium voltage capacitor C ₂ after the secondary winding L _{S is} freewheeled, so that the high voltage circuit 108 outputs the second output current i _O2 such that the second output load R _O2 (for example, moving) The motor of the carrier carries a second output voltage V _O2 . The filter capacitor C _{O2 is} used to provide a smoother voltage source for the second output load R _O2 .

In the practical example, when the switching element S ₁ is turned off and the secondary side winding L _S continues to flow residual residual energy, the diode D ₃ is turned off, and the diode D ₄ is turned on. The high voltage circuit 108 is caused to output a second output voltage V _O2 to drive the motor. In addition, since the transformer of high excitation current (also referred to as coupled inductor) has the function of boosting, and the medium voltage capacitor C ₂ has the function of storing the energy of the secondary side winding L _S , the second output voltage V of the second circuit 12 _{O2 is} higher than the first output voltage V _{O1 of the} first circuit 11.

[Example of operation mode of single-input multi-output DC/DC converter]

For a more clear description of the operation of the single-input multi-output DC/DC converter 10 in each operation mode, please refer to FIG. 3. FIG. 3 illustrates a single-input multi-output DC/DC converter according to an embodiment of the present invention. The equivalent circuit diagram. 3, to simplify the single input multiple output DC / DC converter 10 of the analysis, a capacitance C is assumed here that the _{clamp. 1} and maximum capacitance value of the capacitance C MV _2, and are equivalent to the power supply V _C1 at constant pressure With V _C2 . The coupled inductor T _r can be equivalent to the primary side winding L _P , the primary side magnetizing inductance L _mp , the primary side leakage inductance L _{kp ,} and the secondary side winding L _S . The secondary side winding L _S also has a leakage inductance, but in order to simplify the circuit analysis and description, the leakage inductance of the secondary side winding L _S is considered to be coupled to the primary side leakage inductance L _kp , so it is not shown in FIG. 3 . in. In addition, the control circuit 101 is also not shown in FIG. 3, but does not mean that the control circuit 101 is not required to be provided.

Next, please refer to FIG. 4-1, FIG. 4-2 and FIG. 5 together. FIG. 4-1 is a diagram showing current timing waveforms of a single-input multi-output DC/DC converter according to an embodiment of the present invention. 4-2 is a diagram showing voltage timing waveforms of a single-input multiple-output DC/DC converter according to an embodiment of the present invention. 5A to 5F are schematic diagrams showing circuit operation modes of a single-input multi-output DC/DC converter according to an embodiment of the present invention. The circuit operation of the single-input multiple-output DC/DC converter 10 can be subdivided into six operational modes in accordance with the conduction state of the switching element S ₁ and the diodes D ₁ , D ₂ , D ₃ and D ₄ . In addition, the switching period of the switching element S ₁ is defined as T _S and the duty cycle is d ₁ . Therefore, according to the current voltage timing waveform diagrams of FIGS. 4-1 and 4-2 and the circuit operation mode diagram of FIG. 5, the actual operation of the embodiment of the present invention in each operation mode will be described in detail below.

As shown in FIG. 5A, in the first operation mode ( t ₀ ≦ t < t ₁ ), the switching element S ₁ is turned on, so that the DC input power source V _FC has a primary side leakage inductance L _kp , a primary side winding L _{P ,} and once The side magnetizing inductance L _{mp is} used for excitation charging, and the induced voltage v _{Ls is} generated to the secondary side winding L _S according to the winding turns ratio (also referred to as the turns ratio). At this time, since the second output voltage V _O2 of the second output load carrying R _O2 is greater than the DC input power V _FC, clamp capacitor C _1, and the secondary winding L _S MV voltage across capacitor C _2, so diode The body D _{4 is} not turned on, so that the polarity points of the primary side winding L _P and the secondary side winding L _S are positive, and at the same time, the diode D _{3 is} passed through.

In response to the above, the induced voltage v _{Ls of the} secondary winding L _s can charge the medium voltage capacitor C ₂ via the diode D ₃ by the forward conduction of the diode D ₃ . At the same time, the auxiliary inductor L _aux is releasing the stored residual energy to the first output load R _O1 , in other words, generating the first output voltage V _O1 to charge the battery.

As shown in FIG. 5B, in the second mode of operation ( t ₁ ≦ t < t ₂ ), the switching element S ₁ has been turned on for a period of time, and after the auxiliary inductor L _aux releases the energy, the diode D ₁ is turned off in reverse. The operation of the auxiliary circuit 102 is stopped entirely. At this time, the DC input power source V _FC continues to charge the primary side leakage inductance L _kp , the primary side winding L _P and the primary side excitation inductance L _mp , and generates an induced voltage v _Ls according to the winding turns ratio to the secondary winding. L _s , so that the induced voltage v _Ls can continuously charge the medium voltage capacitor C ₂ through the turned-on diode D ₃ .

Next, as shown in FIG. 5C, in the third operation mode ( t ₂ ≦ t < t ₃ ), the switching element S _{1 is} turned off, and the primary side leakage inductance L _kp needs to be freewheeling, so that the primary side leakage L _kp parasitic capacitance to sense the internal switching element S ₁ is provided (the switching element S ₁ and the counter provided inside of and connected parallel diodes, not shown in this figure) for charging. When the voltage across the switching element S v _{S1 1} is greater than the DC input power V _FC clamp capacitor C ₁ and the voltage across, the switching element S cut the entire conduction path and _a forward conducting diode D _2.

In response to the above, the primary side leakage inductance L _kp and the energy of the primary side winding L _P are continued to the clamp capacitor C ₁ by the turned-on diode D ₂ , that is, the clamp capacitor C ₁ is charged. Thus, by clamping circuit 104 is provided, it can be solved surge (surge) switching element S ₁ when switching problems arising. In addition, part of the energy released by the primary winding L _P charges the auxiliary inductor L _aux , and also passes through the conduction of the diode D ₁ , and outputs a first output voltage V _O1 to charge the battery. At the same time, the secondary side winding L _s needs to renew the residual secondary side leakage inductance energy, and the conduction current diode D ₃ enables the current i _Ls to continuously charge the medium voltage capacitor C ₂ .

After the secondary side leakage inductance energy of the secondary side winding L _s is freewheeled, as shown in FIG. 5D, in the fourth operation mode ( t ₃ ≦ t < t ₄ ), the switching element S ₁ continues to be turned off, but Since the secondary side leakage sensation energy has been continuously flowed, the diode D _{3 is} reversely turned off and the diode D _{4 is} turned on, so that the polarity points of the primary side winding L _P and the secondary side winding L _s are made. Change to negative polarity. At this time, the primary side magnetizing inductance L _mp transmits energy to the secondary side winding L _S via the primary side winding L _P . Therefore, the current path of the clamp capacitor C ₁ , the secondary winding L _S and the medium voltage capacitor C ₂ is constructed by the forward conduction of the diode D ₄ , so that the high voltage circuit 108 can output the second motor capable of driving the motor. Output voltage V _O2 . It is worth noting that the current i _{Lkp of the} primary side leakage inductance L _kp still continuously _charges the auxiliary inductor L _aux , and simultaneously outputs the remaining _unstored energy as the first output voltage V _O1 . The first output voltage V _O1 is caused to charge the battery.

Next, as shown in FIG. 5E, in the fifth mode of operation ( t ₄ ≦ t < t ₅ ), the switching element S ₁ continues to be turned off. At this time, the leakage inductance energy of the primary side leakage inductance L _kp continues to be clamped. Capacitor C ₁ has ended, causing diode D _{2 to turn} off in reverse. Therefore, at this time, the single-input multi-output DC/DC converter 10 can be regarded as two power supply circuits, which are respectively connected to the primary side winding L _P by the DC input power source V _FC (including the primary side leakage inductance L _kp , the primary side winding L _{P ,} and The primary side magnetizing inductance L _mp ) and the auxiliary inductor L _aux , and through the forward-conducting diode D ₁ , the power supply circuit of the first circuit 11 for charging the battery, and the capacitor C _{1 in} series by the DC input power source V _FC The secondary winding L _S and the medium voltage capacitor C ₂ are transmitted through the forward-conducting diode D ₄ to output a power supply circuit of the second circuit 12 capable of driving the second output voltage V _O2 of the motor.

It is worth noting that in the fifth mode of operation ( t ₄ ≦ t < t ₅ ), although the auxiliary inductor L _aux has started to release energy, the auxiliary inductor L _aux is still continuously due to the DC input power source V _FC. The auxiliary inductor L _aux is magnetized so that the current i _Laux curve flowing through the auxiliary inductor L _{aux does} not change significantly. As shown in Figure 4-1, in the time interval [ t ₄ ≦ t < t ₅ ], the current i _{Laux of the} auxiliary inductor L _aux is approximately flat. At this time, the current i _Laux intensity of the auxiliary inductance L _aux is approximately equal to the current i _Lkp intensity of the primary side leakage inductance L _kp .

Finally, as shown in FIG. 5F, in the sixth mode of operation ( t ₅ ≦ t < t ₆ ), the switching element S ₁ receives the control signal and is turned on, so that the current i _Lkp of the primary side leakage inductance L _kp is mostly _Flowing to the ground terminal, the current i _Lkp intensity of the primary side leakage inductance L _kp is not equal to the current i _Laux intensity of the auxiliary inductance L _aux . In this way, the auxiliary inductor L _aux will continuously release the stored residual energy to output the first output voltage V _O1 , so that the battery can be charged. In addition, since the current i _Lkp of the primary side leakage inductance L _kp mostly flows to the ground terminal, the current i _Laux curve of the auxiliary inductance L _aux is in the time interval [ t ₅ ≦ t < t ₆ ] shown in FIG. 4-1. It began to show a linear downward trend.

According to the above, at this time, since the secondary side leakage inductance energy of the secondary side winding L _S needs to be freewheeling, the second output load R _O2 (for example, a motor) can be supplied through the still-on diode D ₄ . The output voltage V _{O2 is} completed until the secondary side leakage inductance is completed, so that the second output voltage V _{O2 is} greater than the voltage across the DC input power source V _FC , the clamp capacitor C ₁ , the secondary side winding L _S and the medium voltage capacitor C ₂ . And the cut-off diode D ₄ , the operation state of the single-input multi-output DC/DC converter 10 returns to the first operation mode again, thus completing a switching cycle.

It is worth noting that since the diode D ₂ has no reverse recovery current at the moment when the switching element S _{1 is} turned on, and the leakage inductance L _{kp of the} primary side winding L _P limits the rising rate of the current i _Lkp , so that the switching element S _{1 The} current cannot be obtained from any path, and zero current switching (ZCS) is formed, which reduces the switching loss, as shown in the time interval shown in Figure 4-1 and Figure 4-2 [ t ₅ ≦ t < t _{In 6} ], v _S1 and i _S1 curves can observe this result. In addition, due to the setting of the clamping circuit 104, the switching element S ₁ can select a field effect transistor of a low voltage level, and at the same time, the problem of conduction loss is reduced because of the low internal resistance characteristic of the field effect transistor.

In practical applications, the DC input power source V _FC is a voltage level that can be output by the fuel cell, the first output voltage V _O1 is a voltage level for providing auxiliary battery floating charge, and the second output voltage V _O2 is for providing a mobile load. Motor-operated operating voltage level. In this way, when the fuel cell drives the mobile carrier, the auxiliary battery is also charged at the same time, so that the balance control system and the fuel cell peripheral device can operate normally.

Generally, the DC input power source V _FC is 12 volts, and the first output voltage V _O1 and the second output voltage V _O2 are 24 to 28 volts respectively through a preset ratio of the number of winding turns and the inductance of the auxiliary inductor L _aux . With 200 volts, the invention is not limited thereto. Among them, the auxiliary battery's floating charging voltage range is 24~28 volts, in which the maximum service life of the auxiliary battery can be maintained. In addition, since the boost ratio of the low voltage circuit 100 to the auxiliary circuit 102 is about 2.33, and the boost ratio of the low voltage circuit 100 to the high voltage circuit 108 is about 16.67, the single input multiple output DC/DC converter 10 has a high step-up ratio. characteristic. It has been experimentally proved that the average conversion efficiency of the single-input multi-output DC/DC converter 10 can reach 91%, and the highest conversion efficiency is higher than 95%.

[Another Embodiment of Single Input Multiple Output DC/DC Converter]

Please refer to FIG. 6. FIG. 6 is a schematic circuit diagram of a single input multi-output DC/DC converter according to another embodiment of the present invention. As shown in FIG. 6, the single-input multiple-output DC/DC converter 10' includes a low-voltage circuit 100, a control circuit 101, an auxiliary circuit 102, an auxiliary sub-circuit 102', a clamp circuit 104, a medium voltage circuit 106, and a high-voltage circuit 108. The coupling relationship between the components of the low-voltage circuit 100, the control circuit 101, the auxiliary circuit 102, the clamp circuit 104, the intermediate voltage circuit 106, and the high-voltage circuit 108 is the same as that of the previous embodiment, and therefore will not be described again.

The only difference is that a single input multiple output DC / DC converter 10 'is designed with further auxiliary sub-circuit 102', the auxiliary sub-circuit 102 'includes an auxiliary sub inductance ^L' _aux, diode D _^'1 (a fifth diode Body), filter capacitor C' _O1 and third output load R ^' _O1 . The first end of the auxiliary sub-inductor L ^' _aux of the auxiliary sub-circuit 102' is coupled to the second end of the primary side winding L _P , the first end of the switching element S ₁ , and the contact of the first end of the auxiliary inductor L _aux . . In addition, the coupling relationship of the remaining electronic components in the auxiliary sub-circuit 102' is the same as that of the auxiliary circuit 102, and therefore will not be described again. In other words, the auxiliary sub-circuit 102' is connected in parallel with the auxiliary circuit 102 in addition to the low voltage circuit 100.

It is worth noting that the auxiliary inductor L ^' _{aux is} also used to temporarily store the energy released by the first magnetic field. Thus, when the pressure is greater than across the diode D between the helper inductance L _^'aux third output load ^R' _O1 ^'when _an ON voltage, the output current of the auxiliary ^sub-i' _O1 to the third output load R _^'O1 So that the third output load R ^' _O1 carries the auxiliary sub-voltage V ^' _O1 . When helper inductance L _^'aux third output load ^R' is smaller than the cross voltage between _O1 diode D ^'when _a turn-on voltage, the helper current ^I' as will _O1 ^'off diode D ₁ And the transition to zero. In addition, since the auxiliary sub-circuit 102' has a detailed operation mode of the circuit as described in the previous auxiliary circuit 102, the operation mode of the single-input multi-output DC/DC converter 10' at each stage will not be described herein.

Because the auxiliary sub-circuit 102' can charge another auxiliary power source. Thus, in practice, the third output load R _^'O1 battery may be another, if this battery float voltage range of 12 to 14 volts, by designing helper inductance ^L' _aux inductance value such that the third output load The auxiliary sub-voltage V ^' _O1 carried by R ^' _O1 is 12-14 volts, and the battery is charged, but the invention is not limited thereto.

In this way, when the DC input power source V _FC charges the first output load R _O1 (for example, the battery), the third output load R _O1 (for example, another battery) is simultaneously charged, and the single input is more The output DC/DC converter 10' can output a second voltage output V _{O2 of a} higher voltage level to a second output load R _O2 (eg, a motor that moves the carrier) by a winding turns ratio.

In addition, although the single-input multi-output DC/DC converter 10' of the embodiment of the present invention is provided with only one auxiliary sub-circuit 102', the auxiliary sub-circuit 102' is not limited to one, and those skilled in the art may Depending on the situation, a plurality of auxiliary sub-circuits are coupled to the contacts of the low voltage circuit 100, the auxiliary circuit 102, and the auxiliary sub-circuit 102', so that a plurality of auxiliary sub-voltages can be provided for a plurality of different loads. Therefore, as can be seen from the above, the single-input multi-output DC/DC converter 10' has scalability.

[Possible efficacy of the embodiment]

In summary, the embodiment of the present invention provides a single-input multi-output DC/DC converter, which has a single-input multi-output DC/DC converter through the setting of an auxiliary circuit and a clamp circuit, and the leakage inductance characteristic of the coupled inductor. Low step-up ratio output voltage source with high step-up ratio output voltage source. In addition, the leakage inductance of the coupled inductor enables the switching element to achieve zero current switching, thereby reducing switching losses and reducing the reverse recovery current of the diode to reduce electromagnetic interference (EMI) in the circuit. In addition, the single-input multi-output DC/DC converter of the embodiment of the present invention only needs to use one set of switching elements, so that the single-input multi-output DC/DC converter can output multiple sets of voltage sources with different voltage levels, which not only reduces the voltage source. The cost of circuit design increases the practicality of practical applications.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the invention.

10, 10'‧‧‧ Single Input Multiple Output DC/DC Converter

11‧‧‧First circuit

12‧‧‧Second circuit

100‧‧‧Low voltage circuit

101‧‧‧Control circuit

102‧‧‧Auxiliary circuit

102'‧‧‧Auxiliary Subcircuit

104‧‧‧Clamping circuit

106‧‧‧ medium voltage circuit

108‧‧‧High voltage circuit

V _FC ‧‧‧DC input power supply

S ₁ ‧‧‧Switching elements

L _P ‧‧‧ primary winding

L _mp ‧‧‧primary side magnetizing inductance

L _kp ‧‧‧Side side leakage inductance

L _S ‧‧‧ secondary winding

L _aux ‧‧‧Auxiliary inductance

L ^' _aux ‧‧‧Auxiliary inductor

D ₁ ~ D ₄ , D ^' ₁ ‧ ‧ diode

C _FC , C _O1 , C _O2 , C ^' _O1 ‧‧‧ Filter Capacitor

C ₁ ‧‧‧Clamping capacitor

C ₂ ‧‧‧ medium voltage capacitor

i _O1 , i _O2 , i _FC , i _C1 , i _Lp , i _Lmp , i _Lkp , i _Ls , i _S1 , i _D2 , i _D3 , i _D4 , i _Laux , i ^' _O1 ‧‧‧ Current

V _O1 , V _O2 , V _FC , V _C1 , V _C2 , v _Lp , v _Lmp , v _Lkp , v _Ls , v _S1 , v _D1 , v _D2 , v _D3 , v _D4 , v _Laux , V ^' _O1 ‧ ‧Voltage

R _O1 , R _O2 , R ^' _O1 ‧‧‧ load

T _S ‧‧‧Switching cycle

d ₁ ‧‧ ‧Liability cycle

t ₀ ~ t ₆ ‧‧‧ time interval

1 is a functional block diagram of a single input multiple output DC/DC converter in accordance with an embodiment of the present invention.

2 is a circuit diagram of a single-input multiple-output DC/DC converter according to an embodiment of the present invention.

3 is an equivalent circuit diagram of a single-input multiple-output DC/DC converter according to an embodiment of the present invention.

4-1 is a diagram showing current timing waveforms of a single-input multiple-output DC/DC converter according to an embodiment of the present invention.

4-2 is a diagram showing voltage timing waveforms of a single-input multiple-output DC/DC converter according to an embodiment of the present invention.

5A to 5F are schematic diagrams showing circuit operation modes of a single-input multi-output DC/DC converter according to an embodiment of the present invention.

6 is a circuit diagram of a single-input multiple-output DC/DC converter according to another embodiment of the present invention.

10. . . Single Input Multiple Output DC/DC Converter

100. . . Low voltage circuit

101. . . Control circuit

102. . . Auxiliary circuit

104. . . Clamp circuit

106. . . Medium voltage circuit

108. . . High voltage circuit

V _FC . . . DC input power

S ₁ . . . Switching element

L _P . . . Primary winding

L _S . . . Secondary winding

L _aux . . . Auxiliary inductance

D ₁ ~ D ₄ . . . Dipole

C _FC , C _O1 , C _O2 . . . Filter capacitor

C ₁ . . . Clamping capacitor

C ₂ . . . Medium voltage capacitor

i _O1 , i _O2 , i _FC . . . Current

V _O1 , V _O2 . . . Voltage

R _O1 , R _O2 . . . load

Claims (9)

A single-input multi-output DC/DC converter includes: a low-voltage circuit having a primary side winding and a switching element coupled between the primary side winding and a ground, and controlled by a The control signal is turned on. When the switching element is turned on, the primary side winding stores energy in a first magnetic field, and when the switching element is turned off, the primary side winding releases energy stored in the first magnetic field; a control circuit coupled to the switching element, the control circuit is configured to control a duty cycle of the switching element by outputting the control signal; an auxiliary circuit coupled to the low voltage circuit, the auxiliary circuit having an auxiliary inductor, the switch The energy released by the primary winding is stored when the component is turned off, and a first output voltage is output according to the energy released by the primary winding and the auxiliary inductor; a medium voltage circuit coupled to the low voltage circuit has a secondary side a winding and a medium voltage capacitor, the secondary side winding generates a potential difference through mutual inductance with the primary side winding, and the secondary side winding is stored when the switching element is turned on And storing the potential difference in the medium voltage capacitor, wherein the secondary side winding continues to flow the potential difference to the medium voltage capacitor when the switching element is turned off; and a high voltage circuit coupled to the medium voltage circuit for receiving the The energy in the medium voltage capacitor outputs a second output voltage; wherein the second output voltage is greater than the first output voltage. The single-input multi-output DC/DC converter according to claim 1, wherein the auxiliary circuit further includes a first diode, and the anode end of the first diode is coupled to the auxiliary inductor. The forward conduction of the first diode causes the auxiliary circuit to output the first output voltage. The single-input multi-output DC/DC converter according to claim 1, wherein the single-input multi-output DC/DC converter further includes: a clamping circuit coupled to the low voltage circuit and the medium voltage Between the circuits, there is a clamp capacitor that stores the leakage inductance energy of the primary side winding when the switching element is momentarily turned off, and the clamp capacitor discharges after the leakage current of the primary side winding is freewheeled. Store the energy to the medium voltage circuit. The single-input multi-output DC/DC converter of claim 3, wherein the clamping circuit further includes a second diode coupled to the anode end of the second diode a first end and a second end of the primary winding, and a cathode end of the second diode is coupled to the clamping capacitor, and the second diode is turned on at the moment when the switching element is turned off, so that the primary side The leakage inductance energy of the winding is stored to the clamp capacitor, and the second diode is cut off when the leakage inductance energy of the primary side winding is completed. The single-input multi-output DC/DC converter according to claim 4, wherein the first end of the secondary winding is coupled to the junction of the second diode and the clamp capacitor, the secondary side The second end of the winding is coupled to the medium voltage capacitor, and the anode end of a third diode of the medium voltage circuit is coupled to the first end of the secondary winding, and the cathode end of the third diode The junction of the medium voltage capacitor and the high voltage circuit is coupled to the third diode by the potential difference generated by the secondary winding. The single-input multi-output DC/DC converter according to claim 5, wherein the high voltage circuit comprises a fourth diode, and the anode end of the fourth diode is coupled to the cathode of the third diode The contact with the intermediate voltage capacitor is extreme, and when the secondary winding is freewheeled, the third diode is turned off and the fourth diode is turned on. The single-input multi-output DC/DC converter according to claim 1, wherein the interface of the low-voltage circuit coupled to the auxiliary circuit has a contact, and at least one auxiliary sub-circuit is coupled to the contact, and each The auxiliary sub-circuit has an auxiliary sub-inductor. When the switching element is turned off, the at least one auxiliary sub-inductor stores the energy released by the primary-side winding, and the energy released according to the primary-side winding and the at least one auxiliary inductor At least one auxiliary sub-voltage is output. The single-input multi-output DC/DC converter according to claim 7, wherein each of the auxiliary sub-circuits further includes a fifth diode, and the anode end of each of the fifth diodes is coupled to each And the auxiliary sub-inductor outputs the at least one auxiliary sub-voltage by the at least one auxiliary sub-circuit by the forward conduction of each of the fifth diodes. The single-input multi-output DC/DC converter according to claim 1, wherein the switching element is a reverse-parallel diode-shaped metal oxide half field effect transistor (MOSFET), and the switching element has a drain The primary side winding is coupled, the source of the switching element is coupled to the ground, and the gate of the switching element is coupled to the control circuit.