TW201810905A - Bidirectional power converter and its operation method which has the function of bidirectional power flow and can effectively enhance the effect of the conversion gain of the buck/boost - Google Patents

Abstract

A bidirectional power converter is coupled among a battery, a supercapacitor, and a driver having a DC bus. The bidirectional power converter includes six switches including a first switch to a sixth switch, and a clamping capacitor. By correspondingly switching the respective switches, the bidirectional power converter of the present invention can provide a plurality of working modes for the user to select. For example, in the forward boost mode, the battery and the supercapacitor can discharge the DC bus of the driver; in the reverse buck mode, the DC bus of the driver can charge the battery and the supercapacitor. The bidirectional power converter of the present invention has the function of bidirectional power flow and can effectively enhance the effect of the conversion gain of the buck/boost. An operation method of the bidirectional power converter includes the steps of detecting the operating state of the driver and executing the operation of the bidirectional power converter according to the operating state of the driver. When the driver is started, loaded, or accelerated, the bidirectional power converter operates in a first mode for controlling the fifth switch and the sixth switch in an off state, controlling the switching of the third switch and the fourth switch by an interleaved switching manner, and controlling the switching of the first switch and the second switch in synchronous rectification mode so that the battery and the supercapacitor supply the energy to the DC bus. When the driver reduces the load or is decelerating, the bidirectional power converter operates in a second mode for controlling the fifth switch and the sixth switch in an off state, controlling the switching of the first switch and the second switch in an interleaved switching manner, and controlling the switching of the third switch and the fourth switch in synchronous rectification mode so that the energy of the DC bus is reversely recovered to charge the battery and the supercapacitor.

Description

Bidirectional power converter

The invention relates to a power converter; in particular, it refers to a bidirectional power converter.

With the people crying out to stop "climate crime" and implement the promise of energy conservation and carbon reduction, the world's first legally binding greenhouse gas reduction agreement, the Paris Agreement, was passed on December 12, 2015, a total of 195 The country reached a global climate change agreement, which has become a historic reform of energy policies in various countries. According to the International Energy Agency (IEA) assessment, according to the goals set out in the agreement, by 2030, countries will invest up to $ 16.5 trillion in renewable energy and energy efficiency. This means that governments must encourage the production of green energy, reduce support for fossil fuels such as oil, and even affect the transportation industry.

At present, among many green energy sources, the application of fuel cells is particularly concerned. The following is an example of the application of fuel cell vehicles. The principle of a fuel cell is based on hydrogen as a fuel, which generates electricity through a proton exchange membrane after an electrochemical reaction with oxygen. The advantages include zero pollution, high efficiency, low noise, low vibration, and long life. They are suitable for use as Replaces traditional gasoline and diesel engines with high pollution and low efficiency. In particular, compared with pure electric vehicles, fuel cell vehicles have the advantage of fast fuel replenishment. From the perspective of electric vehicles produced by American electric vehicle manufacturer Tesla, its electric vehicles are fully charged once. It can take from tens of minutes to several hours. In contrast, fuel cell vehicles can be refueled in just a few minutes. Because of this, fuel cell vehicles have become key technologies that the United States, Japan, and Europe have been rushing to develop in recent years, and they have become rewarded and promoted products in these countries.

Fuel cell generators at this stage mainly have three problems, such as cold start, slow dynamic response, and brake feedback energy storage. Further exploration of its causes is mainly due to the polarization loss at the input end of the fuel cell, which causes the DC voltage at the output end of the fuel cell to appear unstable and respond slowly. In order to enable the fuel cell electric vehicle to adapt to various environments and more driving operating conditions, the powertrain configuration must include on-board auxiliary energy storage elements such as a battery pack or an ultracapacitor. As a result, when the vehicle is operating at low speed, low load, or urban driving, the vehicle power is mainly provided by the battery; when the vehicle is operating at high speed, high load and rapid deceleration, the ultracapacitor can provide rapid acceleration power demand and assist in recovering the brake energy.

In recent years, many experts and scholars have continuously proposed related research topics on the integration and application of power converters, drivers, energy management and charging and discharging technologies in electric vehicle systems. Among them, according to the currently published literature, it can be known that general DC / DC power converters can only transfer energy in one direction. If there is a demand for reverse energy recovery, such as the application of chargers, uninterruptible power systems, and motor brake recharging, It requires another set of DC / DC power converters. However, adding an additional set of power converters will increase the number and size of components and significantly increase costs. Therefore, in recent years, many experts and scholars have successively invested in the research of bidirectional power converters.

Bidirectional power converters can be roughly divided into isolated and nonisolated types. The advantages of isolated converters are the use of high-voltage transformers, electrical isolation, and wide input range through the design of the transformer turns ratio. / Output operating range, etc. However, the existence of leakage inductance and distributed capacitance of high-voltage transformers will make voltage and current surges larger, which will affect the reliability of the overall circuit. In addition, transformers will also cause problems such as loss of efficiency, difficulty in heat dissipation, and occupation of volume. In view of the above problems, non-isolated bidirectional converters are widely used in high power / high efficiency applications. Among them, the simplest non-isolated bidirectional converter is a half-bridge step-up / step-down converter. The working state is divided into step-down and step-up modes, which are used to charge and discharge the battery pack of electric vehicles. The half-bridge converter has a simple architecture and the lowest cost. However, when it is operated in boost mode, the DC bus voltage is easy to drop due to the parasitic effect. As the switching duty cycle increases, the converter efficiency will decrease significantly. On the other hand, its inductor current ripple is large, and it is limited by the gain conversion ratio of the high and low voltage sides. Neither the battery pack nor the DC bus voltage design is suitable for low voltage applications. Therefore, in order to further reduce inductor current ripple and improve efficiency, two-phase or multi-phase interleaved bidirectional power converters are proposed in the literature. However, the interleaving operation of the converter can achieve low ripple requirements. The larger the voltage difference between the input and output of the converter, the non-ideal working condition of the duty cycle of the switch still being too large or too low.

Therefore, the existing bidirectional power converters still have problems such as high system control complexity, high cost, easy operation in non-ideal working conditions, and low conversion efficiency, which need to be improved urgently.

In view of this, the object of the present invention is to provide a bidirectional power converter, which can meet the application scope and development trend of the electric vehicle industry, and can achieve the purpose of suppressing peak loads and improving conversion efficiency, thereby achieving energy saving and carbon reduction.

In order to achieve the above-mentioned object, the present invention provides a bidirectional power converter for coupling between a battery, an ultracapacitor, and a driver; the battery has a positive terminal and a negative terminal; and the driver has a DC bus And the DC bus has a positive terminal and a negative terminal; the bidirectional power converter includes: a first switch having a first terminal and a second terminal; and the second terminal of the first switch and A positive end of the battery is electrically connected; a second switch having a first end and a second end, and the first end of the second switch is electrically connected to the positive end of the DC bus, the second switch A second end of the third switch is electrically connected to the first end of the first switch; a third switch has a first end and a second end; and the second end of the third switch is connected to the negative end of the battery, the The negative terminal of the DC bus is electrically connected. In addition, the third switch is connected in parallel with the ultracapacitor; a fourth switch has a first terminal and a second terminal, and the first terminal of the fourth switch is connected to the first terminal. The second terminal of a switch is electrically connected, and the second terminal of the fourth switch is electrically connected. The negative terminal of the battery and the negative terminal of the DC bus are electrically connected; a fifth switch has a first terminal and a second terminal, the first terminal of the fifth switch and the second terminal of the first switch An electrical connection; a sixth switch having a first end and a second end, the first end of the sixth switch is electrically connected to the first end of the third switch, and the second end of the sixth switch is connected to The second end of the fifth switch is electrically connected; and a clamp capacitor, one end of which is electrically connected to the second end of the second switch, and the other end of which is electrically connected to the first end of the third switch.

According to the above concept, a filter inductor is further included, one end of which is electrically connected to the second terminal of the first switch, and the other end of which is electrically connected to the first terminal of the fifth switch and the positive terminal of the battery.

According to the above concept, when the bidirectional power converter is operated in a first mode, the fifth switch and the sixth switch are controlled to be in an off state, and the third switch and the fourth switch are switched in a staggered manner. The switch performs switch control, and performs synchronous control rectification on the first switch and the second switch; thereby, the battery and the ultracapacitor discharge the DC bus.

According to the above concept, the duty cycle of the third switch and the fourth switch is greater than 50%.

According to the above concept, the third switch and the fourth switch are controlled by an interleaved pulse width modulation signal.

According to the above concept, when the bi-directional power converter is operated in a second mode, the fifth switch and the sixth switch are controlled in an off state, and the first switch and the second switch are switched in an interleaved manner. The switch performs switch control, and the third switch and the fourth switch are controlled by synchronous rectification; thereby, the DC bus charges the battery and the ultra capacitor.

According to the above concept, the duty cycle of the first switch and the second switch is less than 50%.

According to the above concept, the first switch and the second switch are controlled by an interleaved pulse width modulation signal.

According to the above concept, when the bidirectional power converter is operated in a third mode, the first switch, the second switch, the fourth switch, and the sixth switch are controlled to be in an off state, and adjusted by a pulse width. A variable signal drives the fifth switch, and the third switch is used for synchronous rectification, so that the battery releases energy and stores the energy in the ultracapacitor.

According to the above concept, when the bi-directional power converter is operated in a fourth mode, the first switch, the second switch, the fourth switch, and the fifth switch are controlled to be in an off state, and adjusted by a pulse width. A variable signal drives the third switch, and the sixth switch is used for synchronous rectification, so that the ultracapacitor can release energy and store the energy in the battery.

In order to achieve the above objective, the present invention further provides an operation method, which includes the following steps: A. Detecting the operating state of the driver; B. Performing one of the following steps on the bidirectional power converter according to the operating state of the driver. : B1, when the driver is starting, lifting or accelerating, the bi-directional power converter operates in a first mode, which controls the fifth switch and the sixth switch in the off state, and performs an interleaved switching on the The third switch and the fourth switch perform switch control, and the first switch and the second switch are controlled by synchronous rectification; thereby, the battery and the ultra capacitor are supplied with energy to the DC bus; B2, when When the driver is decelerated or decelerated, the bidirectional power converter operates in a second mode, which controls the fifth switch and the sixth switch in an off state, and interleaves the first switch with the first switch. The second switch performs switch control, and the third switch and the fourth switch are controlled by synchronous rectification; thereby, the DC bus is recovered in the reverse direction. Energy and charge the battery and an ultracapacitor.

According to the above concept, when the bidirectional power converter is operated in a third mode, the first switch, the second switch, the fourth switch, and the sixth switch are controlled to be in an off state, and adjusted by a pulse width. A variable signal drives the fifth switch, and the third switch is used for synchronous rectification, so that the battery releases energy and stores the energy in the ultracapacitor.

According to the above concept, when the bi-directional power converter is operated in a fourth mode, the first switch, the second switch, the fourth switch, and the fifth switch are controlled to be in an off state, and adjusted by a pulse width. A variable signal drives the third switch, and the sixth switch is used for synchronous rectification, so that the ultracapacitor can release energy and store the energy in the battery.

The effect of the present invention is that it can effectively reduce the ripple current of the high-voltage side DC bus, achieve the effects of low ripple, boost / buck converter gain improvement, and the characteristics of management and distribution of dual power sources.

In order to explain the present invention more clearly, some embodiments are described in detail below with reference to the drawings. Please refer to FIG. 1, which is a bidirectional power converter 100 according to a first embodiment of the present invention, which is used to be coupled between a battery 10, an ultracapacitor 30 and a driver. The battery 10 has a positive terminal and a Negative end, the driver has a DC bus 20, and the DC bus 20 has a positive end and a negative end. In this embodiment, the DC bus 20 has a specification of DC 600 ~ 700V, but other Actual implementation is not limited to this. Therefore, the electric energy of the storage battery 10 and the ultra capacitor 30 can be transmitted to the driver through the bidirectional power converter 100 for the driver to operate.

The battery 10 can be selected from Lithium Iron Phosphate Oxide (LFPO) batteries, Lithium iron phosphate (LFP) batteries, ternary polymer lithium batteries, and lead-acid batteries. limit. In this embodiment, the battery 10 is a lithium iron oxide phosphate battery, which has the advantages of low cost, high conductivity of the positive electrode material and high number of cycles, low self-discharge rate, and environmental protection. , Its appearance is thin, short, short, and can withstand high voltage and high temperature, so it is especially suitable for the power demand of the driver. In addition, for the convenience of explanation, a single battery 10 is used in this embodiment as an example, and its specification is DC 144V / 15AH, but in other practical implementations, the number of batteries is not limited to a single battery, and it can also be According to the actual working voltage and current requirements, multiple parallel or series batteries are selected for use.

The driver generally refers to a driver for various types of electrical equipment. For example, the driver may be a motor driver for driving a motor of a vehicle, and the vehicle may be an automobile, a locomotive, a ship, an aircraft, etc., and For convenience of explanation, the driver in this embodiment is an electric vehicle motor driver that drives an engine of an electric vehicle, but it is not limited to other practical implementations.

The bidirectional power converter 100 includes a first switch Q ₁ , a second switch Q ₂ , a third switch Q ₃ , a fourth switch Q ₄ , a fifth switch Q ₅ , a sixth switch Q ₆ , a The filter inductor L ₁ , a filter inductor L _2, and a clamping capacitor C _B. In this embodiment, preferably, the first to sixth switches Q ₁ to Q ₆ are selected from metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). In addition, in other applications, other types of switches and voltage control components can be selected according to the use needs, not limited to the above-mentioned MOSFET.

The circuit architecture of the bidirectional power converter 100 of the present invention is described later, in which:

The battery 10 can be equivalent to a voltage source V _BT and a switch Q _BT . The anode of the voltage source V _BT is electrically connected to the first terminal of the switch Q _BT . The anode of the voltage source V _BT constitutes the negative terminal of the battery; the second terminal of the switch Q _BT constitutes the positive terminal of the battery.

The first switch Q ₁ has a first terminal and a second terminal, and the second terminal of the first switch Q ₁ is electrically connected to the positive terminal of the battery 10.

The second switch Q _2, having a first end and a second end and a first terminal of the second switch Q ₂ and the DC busbar is electrically connected to the positive terminal 20, the first and the second switch Q ₂ is The two terminals are electrically connected to the first terminal of the first switch Q ₁ .

The third switch Q ₃ has a first terminal and a second terminal, and the second terminal of the third switch Q ₃ is electrically connected to the negative terminal of the battery 10 and the negative terminal of the DC bus 20.

The fourth switch Q ₄ has a first terminal and a second terminal, and a first terminal of the fourth switch Q ₄ is electrically connected to a second terminal of the first switch Q _1. The fourth switch Q ₄ The second terminal is electrically connected to the negative terminal of the battery 10 and the negative terminal of the DC bus 20.

The fifth switch Q ₅ has a first terminal and a second terminal, and a first terminal of the fifth switch Q ₅ is electrically connected to a second terminal of the first switch Q ₁ .

The sixth switch Q _6, having a first end and a second end, the first end of the sixth switch Q ₆ with the third switch terminal is electrically connected to a first Q _3, Q ₆ of the sixth switch The second terminal is electrically connected to the second terminal of the fifth switch Q ₅ .

The ultracapacitor 30 is connected in parallel with the third switch Q _3. In this embodiment, its specification is DC 72V / 500F, but it is not limited to other practical implementations. The capacitor 30 can be equivalent to a voltage source V _UC , a switch Q _UC, and a filter inductor L _2. The negative electrode of the voltage source V _UC is electrically connected to the negative terminal of the battery. The positive electrode of the voltage source V _UC is connected to the switch. The first end of Q _UC is electrically connected; the second end of the switch Q _UC is electrically connected to one end of the filter inductor L _2; the other end of the filter inductor L _{2 is} electrically connected to the first end of the third switch Q ₃ connection.

In this embodiment, the first terminal of the first to sixth switches Q ₁ to Q _{6 is} a drain terminal, and the second terminal is a source terminal. In addition, when other types of switches are used, the first terminal is not limited to the drain terminal, and the second terminal is not limited to the source terminal.

In addition, each of the aforementioned open relationships can be operated in different working areas by control signals output by one or more controllers (not shown), such as on and off. Therefore, by controlling each switch to operate under different working conditions, the bidirectional power converter of the present invention can have multiple working modes, which are described in detail as follows:

As shown in FIG. 2, when the bidirectional power converter 100 is operated in a first mode (also referred to as a forward boost mode), an output signal controls the fifth switch Q ₅ and the sixth switch Q ₆ in Off state, and switch control of the third switch Q ₃ and the fourth switch Q ₄ in a staggered switching manner, and switch control of the first switch Q ₁ and the second switch Q ₂ in a synchronous rectification manner, At this time, it is in a state of dual-energy power supply, that is, the battery 10 and the ultracapacitor 30 are used to discharge the DC bus 20 together.

It can be seen from FIG. 3 that in the forward boost mode, the battery 10 and the ultracapacitor 30 are discharged, and because the bidirectional power converter 100 uses an interleaved switching operation, the current flowing into the DC bus can be effectively reduced. Ripples. In addition, by simultaneously inputting the electric energy released by the storage battery 10 and the ultracapacitor 30 and boosting it to more than 650V through the bidirectional power converter 100, the problem of insufficient response of conventional fuel cells in electric vehicle systems or energy shortage can be effectively compensated.

Through steady state analysis, the gain (Conversion Gain) of the bidirectional power converter 100 in forward boost mode can be derived as follows (1): = ; V _s1 = kV _s2 ; (1) where k is defined as the ratio between two input voltage sources, V _s1 = V _BT , V _s2 = V _UC . The conversion ratio of the voltage V _H of the DC bus 20 to each input voltage can be further derived as follows (2), (3): = ; (2) = (3) Among them, _{Du is} defined as the duty cycle of the third switch Q ₃ and the fourth switch Q ₄ .

Please also cooperate with the conversion ratio diagrams shown in Figures 4A and 4B. From the figure, it can be seen that as the duty cycle _Du increases, or the voltage of the battery 10 (V _s1 = V _BT ) and the ultracapacitor 30 (V _s2 = V _UC ) When the ratio of the voltage increases, the conversion ratio between the voltage of the DC bus 20 and the battery 10 and the ultracapacitor 30 also increases. Are preferred, _{Q. 3} a third switch, a fourth switch Q _4, the duty cycle may be set based D _u greater than 50%, while the preferred energy conversion ratio can be obtained.

Please refer to FIG. 5, when the bidirectional power converter 100 is operated in a second mode (also referred to as a reverse buck mode), an output signal controls the fifth switch Q ₅ and the sixth switch Q ₆ to be turned off. State, and switch control of the first switch Q ₁ and the second switch Q ₂ in a staggered switching manner, and switch control of the third switch Q ₃ and the fourth switch Q ₄ in a synchronous rectification manner. At this time, it is in a state of charging with dual energy sources, that is, the DC bus 20 charges the battery 10 and the ultracapacitor 30.

Observing FIG. 6 shows that in the reverse step-down mode, the DC bus 20 can charge the battery 10 and the ultracapacitor 30. Therefore, when the motor brakes, the voltage of the DC bus 20 rises rapidly, and the instantaneous high current After the inrush, it can be absorbed by the ultracapacitor 30. In addition, when the vehicle is idling or decelerating, the excess energy released by the other fuel cell should be supplied to the storage battery 10 or the ultracapacitor 30 for storage.

In addition, through the staggered switching operation of the bidirectional power converter 100 in the step-down manner, the current ripple flowing out of the DC bus 20 can be effectively reduced, and the charging current provided to the battery 10 and the ultracapacitor 30 can be stable Continuous waveform.

Through steady state analysis, the gain (Conversion Gain) of the bidirectional power converter 100 in the reverse buck mode can be derived as follows (4): = ; V _s1 = kV _s2 ; (4) where k is defined as the ratio between two input voltage sources, V _s1 = V _BT , and V _s2 = V _UC . The conversion ratio of each input voltage to the DC bus 20 voltage V _H can be further derived as follows (5), (6): = ; (2) = (3) where D _{d is} defined as the duty cycle of the first switch Q ₁ and the second switch Q ₂ .

Please also cooperate with the conversion ratio diagrams shown in Figures 7A and 7B. From the figure, it can be seen that as the duty cycle D _d decreases, or the voltage of the battery 10 (V _s1 = V _BT ) and the voltage of the ultracapacitor 30 (V _s2 = V _As the ratio of _UC ) increases, the step-down conversion ratio of the DC bus 20 voltage to the battery 10 and the ultracapacitor 30 also increases, that is, the DC bus 20 voltage can obtain a lower voltage through the bidirectional power converter 100 of the present invention. Level. Preferably, the duty cycle D _d of the first switch Q ₁ and the second switch Q ₂ can be set to less than 50%, and a better energy conversion ratio can be obtained.

Please cooperate with FIG. 8 and FIG. 9, when the bi-directional power converter 100 is operated in a third mode, output signals control the first switch Q ₁ , the second switch Q ₂ , the fourth switch Q ₄ and The sixth switch Q _{6 is} in the off state. At this time, the DC bus 20 is in an offline mode. Then, the fifth switch Q _{5 is} driven by a pulse width modulation signal, and the third switch Q _{3 is} used for synchronous rectification. At this time, the battery 10 can be released for energy and stored in the ultra capacitor 30.

Among them, the fifth switch Q ₅ and the sixth switch Q ₆ form a bidirectional switch. When the fifth switch Q _{5 is} turned on and the sixth switch Q _{6 is} turned off, a current flows through the diode in the sixth switch Q ₆ to Energy storage for the ultracapacitor 30.

In addition, please cooperate with FIG. 8 and FIG. 10, when the bi-directional power converter 100 is operated in a fourth mode, an output signal controls the first switch Q ₁ , the second switch Q ₂ , and the fourth switch Q. ₄ and the fifth switch Q _{5 is} in the off state. At this time, the DC bus 20 is in the offline mode. Then, the third switch Q _{3 is} driven by a pulse width modulation signal, and the sixth switch Q ₆ is synchronized. For rectification, at this time, the super capacitor 30 can be boosted, energy released and stored in the battery 10.

When the sixth switch Q _{6 is} turned on and the fifth switch Q _{5 is} turned off, a current flows through the diode in the fifth switch Q ₅ to store energy in the battery 10.

It is worth mentioning that the aforementioned drive signal for driving each of the switches is a pulse-width modulation (Pulse-Width Modulation) signal, preferably, in this embodiment, an interleaved pulse-width modulation (Interleaved (Pulse-Width Modulation) signal is preferred, but in other embodiments, other types of control signals or other types of pulse width modulation signals may be selected according to actual needs, instead of the interleaved pulse width modulation described above. The signal is limited.

In addition, the clamping capacitor C _B is coupled between the two-phase circuits of the bidirectional power converter 100, that is, between the second terminal of the second switch Q _{2 and} the first terminal of the fourth switch Q _4. The clamping capacitor C _B can be equivalent to a stable DC voltage source when the bidirectional power converter 100 is in a steady-state operation state, thereby suppressing a two-phase circuit (the first switch Q ₁ and the second switch Q ₂ , the third switch The voltage surges of the switches Q ₃ and the fourth switch Q ₄ ), so that the voltage stress of the switches are clamped in a lower range, and the switching loss is reduced, so as to improve the overall efficiency of the converter.

It is worth mentioning that the bidirectional power converter of the present invention can be used with a detector (not shown), wherein the detector can be electrically connected to the driver for detecting the driver's The operating state, and returns the operating state to a processor or a controller (such as the aforementioned controller) for receiving, and the processor or the controller corresponds to the switches of the bidirectional power converter according to the operating state of the driver control.

For example, when the driver is starting, lifting, or accelerating, it can control the bidirectional power converter 100 to operate in the first mode, that is, control the fifth switch Q ₅ and the sixth switch Q ₆ in the off state. The third switch Q ₃ and the fourth switch Q ₄ are switched in an interleaved switching manner, and the first switch Q ₁ and the second switch Q ₂ are switched in a synchronous rectification manner. The battery 10 and the ultracapacitor 30 supply energy to the DC bus 20.

In addition, when the driver is decelerating or decelerating, the bi-directional power converter 100 can be controlled to operate in the second mode, that is, the fifth switch Q ₅ and the sixth switch Q _{6 are controlled to be} in an off state and switched in an interleaved manner. The first switch Q ₁ and the second switch Q ₂ are switched on and off, and the third switch Q ₃ and the fourth switch Q ₄ are switched on and off in a synchronous rectification manner; thereby, the DC bus 20 is reversely recovered. Charge the battery 10 and the ultracapacitor 30.

In addition, when the DC bus is in an offline mode, the bidirectional power converter 100 can be controlled to operate in the third mode or the fourth mode. Wherein, in the third mode, the first switch Q ₁ , the second switch Q ₂ , the fourth switch Q ₄ and the sixth switch Q _{6 are controlled to be} in an off state and driven by a pulse width modulation signal. The fifth switch Q ₅ and the third switch Q _{3 are} used for synchronous rectification, so that the battery 10 releases energy and stores the energy in the ultracapacitor 30. Wherein, in the fourth mode, the first switch Q ₁ , the second switch Q ₂ , the fourth switch Q ₄ and the fifth switch Q _{5 are controlled to be} in an off state and driven by a pulse width modulation signal. The third switch Q ₃ and the sixth switch Q _{6 are} used for synchronous rectification, so that the ultracapacitor 30 releases energy and stores the energy in the battery 10.

Therefore, through the circuit structure and operation method of the bidirectional power converter described above, and integrated control of the interleaved pulse width modulation signal, the bidirectional power converter of the present invention can effectively reduce the ripple of the DC bus of the motor driver. Effect, and help boost the gain of the buck / buck converter, and achieve the effect of proper management of dual power energy management and distribution.

The above description is only the preferred and feasible embodiment of the present invention. The bidirectional power converter of the present invention can be applied to vehicles, vehicles, and other vehicles, but is not limited thereto. For example, in the field of related electric energy conversion of distributed renewable energy (wind, geothermal, solar, etc.) systems, the bidirectional power converter of the present invention can be applied, not limited to the field of mobile vehicles. The bidirectional power converter of the present invention has high conversion efficiency, conforms to the current application scope and development trend of the green energy industry, and is quite helpful to national energy saving policies.

For example, equivalent changes in the scope of the present invention and the scope of patent application should be included in the scope of patent of the present invention.

[this invention]
100‧‧‧ Bidirectional Power Converter
10‧‧‧ Battery
20‧‧‧DC bus
30‧‧‧ Ultracapacitor
Q ₁ ‧‧‧First switch
Q ₂ ‧‧‧First switch
Q ₃ ‧‧‧Second switch
Q ₄ ‧‧‧Fourth switch
Q ₅ ‧‧‧Fifth switch
Q ₆ ‧‧‧Sixth switch
Q _BT ‧‧‧Switch
Q _UC ‧‧‧Switch
C _B ‧‧‧Clamping Capacitor
L ₁ ‧‧‧filter inductor
L ₂ ‧‧‧filter inductor
V _BT ‧‧‧ Voltage source
V _UC ‧‧‧ Voltage Source
V _H ‧‧‧Voltage
V _gs1 ‧‧‧ Gate source voltage of the first switch
V _gs2 ‧‧‧ Gate source voltage of the second switch
V _gs3 ‧‧‧ Gate source voltage of the third switch
V _gs4 ‧‧‧ Gate source voltage of the fourth switch
V _gs5 ‧‧‧ Gate source voltage of fifth switch

FIG. 1 is an equivalent circuit diagram of a bidirectional power converter according to a first embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of the bidirectional power converter operating in the first mode (forward boost mode) of the above embodiment. FIG. 3 is a driving waveform diagram of a first switch to a fourth switch, a battery / capacitor current and an output voltage waveform diagram when the bidirectional power converter of the above embodiment is operated in the first mode. 4A and 4B are diagrams showing the relationship of the conversion ratio of the DC bus voltage to different input energy sources when the bidirectional power converter of the above embodiment is operated in the first mode. FIG. 5 is an equivalent circuit diagram of the bidirectional power converter in the above embodiment operating in the second mode (reverse buck mode). FIG. 6 is a driving waveform diagram of the first to fourth switches, a current of the battery / capacitor, and an output voltage waveform of the bidirectional power converter in the above embodiment when it is operated in the second mode. FIGS. 7A and 7B are diagrams showing the relationship of the conversion ratio of the DC bus voltage to different input energy sources when the bidirectional power converter of the above embodiment is operated in the second mode. FIG. 8 is an equivalent circuit diagram when the bidirectional power converter of the above embodiment is operated in the third mode or the fourth mode. FIG. 9 is a driving waveform diagram of the fifth switch when the bidirectional power converter of the above embodiment is operated in the third mode, and a waveform diagram of the storage capacity of the battery to the capacitor. FIG. 10 is a driving waveform diagram of the third switch when the bidirectional power converter of the above embodiment is operated in the fourth mode, and a waveform diagram of the capacitor releasing energy to the battery.

100‧‧‧ Bidirectional Power Converter

10‧‧‧ Battery

20‧‧‧DC bus

30‧‧‧ Ultracapacitor

Claims (14)

A bidirectional power converter is coupled between a battery, an ultracapacitor and a driver. The battery has a positive terminal and a negative terminal. The driver has a DC bus and the DC bus has a positive And a negative terminal; the bidirectional power converter includes: a first switch having a first terminal and a second terminal, and the second terminal of the first switch is electrically connected to the positive terminal of the battery; The second switch has a first end and a second end, and the first end of the second switch is electrically connected to the positive end of the DC bus, and the second end of the second switch is connected to the first switch. The first terminal is electrically connected; a third switch has a first terminal and a second terminal, and the second terminal of the third switch is electrically connected to the negative terminal of the battery and the negative terminal of the DC bus, In addition, the third switch is connected in parallel with the ultracapacitor; a fourth switch has a first end and a second end, and the first end of the fourth switch is electrically connected to the second end of the first switch, the The second terminal of the fourth switch, the negative terminal of the battery, and the DC bus A negative terminal is electrically connected; a fifth switch having a first terminal and a second terminal, a first terminal of the fifth switch is electrically connected to a second terminal of the first switch; a sixth switch having A first end and a second end, the first end of the sixth switch is electrically connected to the first end of the third switch, and the second end of the sixth switch is electrically connected to the second end of the fifth switch Connection; and a clamp capacitor, one end of which is electrically connected to the second end of the second switch, and the other end of which is electrically connected to the first end of the third switch. The bidirectional power converter according to claim 1, further comprising a filter inductor, one end of which is electrically connected to the second end of the first switch, the other end is connected to the first end of the fifth switch, and the positive end of the battery. Electrical connection. The bi-directional power converter according to claim 1, wherein when the bi-directional power converter is operated in a first mode, the fifth switch and the sixth switch are controlled in an off state, and the switching is performed in an interleaved manner. The third switch and the fourth switch perform switch control, and the first switch and the second switch are controlled by synchronous rectification; thereby, the battery and the ultracapacitor discharge the DC bus. The bidirectional power converter according to claim 3, wherein the duty cycle of the third switch and the fourth switch is greater than 50%. The bidirectional power converter according to claim 3 or 4, wherein the third switch and the fourth switch are controlled by an interleaved pulse width modulation signal. The bi-directional power converter according to claim 1, wherein when the bi-directional power converter is operated in a second mode, the fifth switch and the sixth switch are controlled in an off state, and the switching is performed in an interleaved manner. The first switch and the second switch perform switch control, and the third switch and the fourth switch are controlled by synchronous rectification. The DC bus is used to charge the battery and the ultra capacitor. The bidirectional power converter according to claim 6, wherein the duty cycle of the first switch and the second switch is less than 50%. The bidirectional power converter according to claim 6 or 7, wherein the first switch and the second switch are controlled by an interleaved pulse width modulation signal. The bidirectional power converter according to claim 1, wherein when the bidirectional power converter is operated in a third mode, the first switch, the second switch, the fourth switch, and the sixth switch are controlled to be turned off. State, and the fifth switch is driven with a pulse width modulation signal, and the third switch is used for synchronous rectification, so that the battery is released for energy and stored in the ultracapacitor. The bidirectional power converter according to claim 1, wherein when the bidirectional power converter is operated in a fourth mode, the first switch, the second switch, the fourth switch, and the fifth switch are controlled to be turned off. State, and the third switch is driven with a pulse width modulation signal, and the sixth switch is used for synchronous rectification, so that the ultracapacitor is released energy and stored in the battery. The bidirectional power converter according to claim 1, wherein the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch are respectively a metal oxide semiconductor field These first ends are the drains of the metal oxide semiconductor field effect transistors, and the second ends are the sources of the metal oxide semiconductor field effect transistors. An operating method applied to the bi-directional power converter according to claim 1, comprising the following steps: A. Detecting the operating state of the driver; B. Operating the bi-directional power converter according to the operating state of the driver. One of the following steps: B1. When the driver is starting, lifting or accelerating, the bi-directional power converter operates in a first mode, which controls the fifth switch and the sixth switch in the off state, and uses an interleaved mode. The switching mode is to switch control the third switch and the fourth switch, and to switch control the first switch and the second switch in a synchronous rectification manner, so that the battery and the ultracapacitor supply energy to the DC bus. B2, when the driver is decelerating or decelerating, the bi-directional power converter operates in a second mode, which controls the fifth switch and the sixth switch in the off state, and interleaves the first switch in a staggered manner. A switch and the second switch perform switch control, and the third switch and the fourth switch are controlled by synchronous rectification; thereby, the reverse recovery is performed. Flow energy bus and the battery and to charge the super capacitor. The method for operating a bidirectional power converter according to claim 12, wherein when the bidirectional power converter is operated in a third mode, the first switch, the second switch, the fourth switch and the sixth switch are controlled. The switch is in an off state, and the fifth switch is driven by a pulse width modulation signal, and the third switch is used for synchronous rectification, so that the battery is released for energy and stored in the ultracapacitor. The method for operating a bidirectional power converter according to claim 12, wherein when the bidirectional power converter is operated in a fourth mode, the first switch, the second switch, the fourth switch and the fifth switch are controlled. The switch is in an off state, and the third switch is driven by a pulse width modulation signal, and the sixth switch is used for synchronous rectification, so that the ultracapacitor is released energy and stored in the battery.