Patent Application
20130088196
The present invention relates to a high-voltage battery charging system, and more particularly to a high-voltage battery charging system for use in an electric vehicle. The present invention relates to a charger with such a high-voltage battery charging system.
Fossil fuels such as petroleum and coal are widely used in automobiles or power plants for generating motive force or electrical power. As known, burning fossil fuels produces waste gases and carbon oxide. The waste gases may pollute the air. In addition, carbon dioxide is considered to be a major cause of the enhanced greenhouse effect. It is estimated that the world's oils supply would be depleted in the next several decades. The oil depletion may lead to global economic crisis.
Consequently, there are growing demands on clean and renewable energy. Recently, electric vehicles and plug-in hybrid electric vehicles have been researched and developed. Electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) use electrical generators to generate electricity. In comparison with the conventional gasoline vehicles and diesel vehicles, the electric vehicles and hybrid electric vehicles are advantageous because of low pollution, low noise and better energy utilization. The uses of the electric vehicles and hybrid electric vehicles can reduce carbon dioxide emission in order to decelerate the greenhouse effect.
As known, an electric vehicle or a plug-in hybrid electric vehicle has a built-in battery as a stable energy source for providing electric energy for powering the vehicle. In a case that the electric energy stored in the battery is exhausted, the battery is usually charged by a charger. The conventional charger comprises a power factor correction circuit, a bus capacitor and a DC-DC converting circuit. The power factor correction circuit is used for increasing the power factor of an input voltage and generating a bus voltage. The bus capacitor is connected with the output terminal of the power factor correction circuit for energy storage and voltage stabilization. The DC-DC converting circuit is used for receiving the bus voltage and converting the bus voltage into a high charging voltage, thereby charging a high-voltage battery unit.
Generally, the magnitude of the bus voltage generated by the power factor correction circuit is dependent on the rated voltage value of the bus capacitor, and the range of the high charging voltage outputted from the DC-DC converting circuit is dependent on the magnitude of the bus voltage. For widening the range of the high charging voltage to have the high charging voltage (e.g. 400V) to charge the high-voltage battery unit, the bus voltage should be higher than 450V for example. Consequently, the bus capacitor of the charger should have a higher rated voltage value (e.g. >500V). Since the bus capacitor with the high rated voltage value is difficultly available and costly, it is not easy to widen the range of the high charging voltage.
Moreover, the charger of the conventional electric vehicle or the conventional plug-in hybrid electric vehicle further comprises an auxiliary power circuit. The auxiliary power circuit is connected with the output terminal of the power factor correction circuit for providing electric energy to various controlling units of the electric vehicle. The bus voltage is served as the input voltage of the auxiliary power circuit. If the input voltage received by the power factor correction circuit is abnormal or interrupted, the power factor correction circuit fails to generate the bus voltage. Under this circumstance, the auxiliary power circuit is disabled and fails to provide electric energy to various controlling units, the functions controlled by these controlling units will be lost.
Moreover, the bus capacitor of the charger for the electric vehicle is usually non-replaceable. Once the bus capacitor is damaged or used for a long time, the whole charger should be replaced with a new one in order replace the bus capacitor. In other words, the conventional high-voltage battery charging system is neither cost-effective nor resource-saving.
Therefore, there is a need of providing high-voltage battery charging system for use in an electric vehicle and a charger thereof in order to obviate the drawbacks encountered in the prior art.
The present invention provides a high-voltage battery charging system for use in an electric vehicle and also a charger with such a high-voltage battery charging system, in which a wide range of a high charging voltage is provided to charge the high-voltage battery unit. Even if the AC input voltage received by the high-voltage battery charging system is abnormal or interrupted, the high-voltage battery charging system can continuously deliver electric energy to various controlling units, consequently, the reliability of the high-voltage battery charging system is enhanced. Moreover, the bus capacitor is replaceable.
In accordance with an aspect of the present invention, there is provided a high-voltage battery charging system. The high-voltage battery charging system includes a rectifier circuit, a power factor correction circuit, a bus capacitor, an intermediate non-isolated DC-DC converting circuit, an intermediate output capacitor, and a non-isolated DC-DC converting circuit. The rectifier circuit is connected with a common terminal for rectifying an AC input voltage into a rectified voltage. The power factor correction circuit is connected to the rectifier circuit for increasing a power factor of the rectified voltage and generating a bus voltage. The bus capacitor is connected between an output terminal of the power factor correction circuit and the common terminal for energy storage and voltage stabilization. The intermediate non-isolated DC-DC converting circuit is connected with the output terminal of the power factor correction circuit and the bus capacitor for boosting the bus voltage into an intermediate output voltage. The intermediate output capacitor is connected between an output terminal of the intermediate non-isolated DC-DC converting circuit and the common terminal for energy storage and voltage stabilization. The non-isolated DC-DC converting circuit is connected with the output terminal of the intermediate non-isolated DC-DC converting circuit, the intermediate output capacitor and a high-voltage battery unit for converting the intermediate output voltage into a high charging voltage, thereby charging the high-voltage battery unit.
In accordance with another aspect of the present invention, there is provided a charger for use in an electric vehicle. The charger includes a charger body, a partition plate assembly, and a circuit board. The partition plate assembly is disposed within the charger body, and having a perforation. The circuit board is partially enclosed within the charger body through the partition plate assembly, and includes a first connecting part and the high-voltage battery charging system of the present invention. The bus capacitor of the high-voltage battery charging system, a supporting plate, a covering member and a second connecting part are collaboratively defined as a replaceable bus capacitor module. The supporting plate is disposed on the partition plate assembly. The second connecting part is electrically connected with the bus capacitor and detachably connected with the first connecting part. The covering member is disposed on the supporting plate for sheltering the bus capacitor. The first connecting part is protruded out over the partition plate assembly through the perforation. The first connecting part is connected with the output terminal of the power factor correction circuit and the intermediate non-isolated DC-DC converting circuit. For replacing the bus capacitor, the first connecting part is detached from the second connecting part and the bus capacitor module with a new one.
The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:
The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.
In this embodiment, the high-voltage battery charging system further comprises an electromagnetic interference (EMI) filtering circuit 7. The EMI filtering circuit 7 is connected to the input terminal of the rectifier circuit 3 for filtering off the surge and high-frequency noise contained in the AC input voltage Vin and the AC input current Iin. In addition, the use of the EMI filtering circuit 7 can reduce the electromagnetic interference on the AC input voltage Vin and the AC input current resulted from the switching circuits of the power factor correction circuit 4, the intermediate non-isolated DC-DC converting circuit 5 and the non-isolated DC-DC converting circuit 6. After the surge and high-frequency noise are filtered off by the EMI filtering circuit 7, the AC input voltage Vin and the AC input current Iin are transmitted to the input terminal of the rectifier circuit 3. The AC input voltage Vin is rectified into a rectified voltage Vr by the rectifier circuit 3.
The power factor correction circuit 4 is connected with the output terminal of the rectifier circuit 3 for increasing the power factor and generating a bus voltage Vbus. The bus capacitor Cbus is connected between the output terminal of the power factor correction circuit 4 and a common terminal COM for energy storage and voltage stabilization. An example of the bus capacitor Cbus includes but is not limited to an electrolytic capacitor.
The intermediate non-isolated DC-DC converting circuit 5 is connected with the output terminal of the power factor correction circuit 4 and the bus capacitor Cbus. The intermediate non-isolated DC-DC converting circuit 5 is used for increasing the bus voltage Vbus into an intermediate output voltage Vi. The intermediate output capacitor Ci is connected between the output terminal of the intermediate non-isolated DC-DC converting circuit 5 and the common terminal COM for energy storage and voltage stabilization. An example of the intermediate output capacitor Ci includes but is not limited to a plastic capacitor. The non-isolated DC-DC converting circuit 6 is connected between the output terminal of the intermediate non-isolated DC-DC converting circuit 5, the intermediate output capacitor Ci and the high-voltage battery unit 2. The non-isolated DC-DC converting circuit 6 is used for converting the intermediate output voltage Vi into a high charging voltage VHb. The high-voltage battery unit 2 is charged by the high charging voltage VHb. In accordance with the present invention, no transformer is included in the electric energy paths of the intermediate non-isolated DC-DC converting circuit 5 and the non-isolated DC-DC converting circuit 6, so that the power loss is largely reduced. Moreover, by a switching circuit and an output filter circuit of the non-isolated DC-DC converting circuit 6, the high-voltage battery unit 2 is charged by the high charging voltage VHb.
In comparison with the conventional charger for an electric vehicle, the high-voltage battery charging system of the present invention further comprises the intermediate non-isolated DC-DC converting circuit 5. The intermediate non-isolated DC-DC converting circuit 5 is arranged between the power factor correction circuit 4 and the non-isolated DC-DC converting circuit 6. Since the input voltage (i.e. the bus voltage Vbus) received by the intermediate non-isolated DC-DC converting circuit 5 has been previously stored and stabilized by the bus capacitor Cbus, the intermediate output voltage Vi is more stable than the bus voltage Vbus. Under this circumstance, the capacitance value of the intermediate output capacitor Ci is lower than that of the bus capacitor Cbus, but the rated voltage value of the intermediate output capacitor Ci is higher than the bus capacitor Cbus. An example of the intermediate output capacitor Ci includes but is not limited to a plastic capacitor. Consequently, the non-isolated DC-DC converting circuit 6 can generate a wide range of the high charging voltage to charge the high-voltage battery unit 2.
In this embodiment, the magnitude of the AC input voltage Vin is 110˜380 volts, the magnitude of the bus voltage Vbus is 350˜450V, the magnitude of the intermediate output voltage Vi is for example 500V, and the magnitude of the high charging voltage VHb is 370˜450V. The capacitance value and the rated voltage value of the bus capacitor Cbus are 100 μF and 450V, respectively. The capacitance value and the rated voltage value of the intermediate output capacitor Ci are 1˜3 μF and 630V, respectively. The rectifier circuit 3, the power factor correction circuit 4, the intermediate non-isolated DC-DC converting circuit 5, the non-isolated DC-DC converting circuit 6, the EMI filtering circuit 7 and the bus capacitor Cbus, the intermediate output capacitor Ci and the high-voltage battery unit 2 are all operated at high voltage values. Consequently, the high-voltage battery charging system has low charging loss and short charging time during the charging process and has low power loss and enhanced efficiency during the electric vehicle is driven.
An example of the intermediate non-isolated DC-DC converting circuit 5 includes but is not limited to a boost non-isolated DC-DC converting circuit. An example of the non-isolated DC-DC converting circuit 6 includes but is not limited to a buck non-isolated DC-DC converting circuit, a buck-boost non-isolated DC-DC converting circuit or a boost non-isolated DC-DC converting circuit. An example of the power factor correction circuit 4 includes but is not limited to a continuous conduction mode (CCM) boost power factor correction circuit, a direct coupling modulated bias (DCMB) boost power factor correction circuit, a buck power factor correction circuit or a buck-boost power factor correction circuit. The high-voltage battery unit 2 includes one or more batteries such as lead-acid batteries, nickel-cadmium batteries, nickel iron batteries, nickel-metal hydride batteries, lithium-ion batteries, or a combination thereof.
As shown in
In a case that the first switching circuit 41 is conducted, the first inductor L1 is in a charging status and the magnitude of the first current I1 is increased. The first current I1 will be transmitted from the first inductor L1 to the first current-detecting circuit 42 through the first switching circuit 41, so that a current-detecting signal Vs is generated by the first current-detecting circuit 42. Whereas, in a case that the first switching circuit 41 is shut off, the first inductor L1 is in a discharging status and the magnitude of the first current I1 is decreased. The first current I1 will be transmitted to the bus capacitor Cbus through the first diode D1.
In this embodiment, the power factor correction controlling unit 43 comprises an input waveform detecting circuit 431, a first feedback circuit 432, and a power factor correction controller 433. The input waveform detecting circuit 431 is connected to the input terminal of the power factor correction circuit 4, the power factor correction controller 433 and the common terminal COM. The input waveform detecting circuit 431 is used for reducing the magnitude of the rectified voltage Vr and filtering off the high-frequency noise contained in the rectified voltage Vr, thereby generating an input detecting signal Vra. After the AC input voltage Vin is rectified, the waveform of the input detecting signal Vra is identical to that of the rectified AC input voltage Vin. The first feedback circuit 432 is connected to the output terminal of the power factor correction circuit 4, the power factor correction controller 433 and the common terminal COM. The first feedback circuit 432 is used for performing voltage division on the bus voltage Vbus, thereby generating a first feedback signal Vf1.
In other words, the waveform of the AC input voltage Vin is acquired by the power factor correction controller 433 according to the input detecting signal Vra. According to the first feedback signal Vf1, the power factor correction controller 433 judges whether the bus voltage Vbus is maintained at the rated voltage value (e.g. 450V). According to the current-detecting signal Vs, the increase magnitude of the first current I1 is detected so as to control the duty cycle of the first switching circuit 41. As a consequence, the bus voltage Vbus is maintained at the rated voltage value, and the distribution of the AC input current Iin is similar to the waveform of the AC input voltage Vin. Under this circumstance, a better power factor correction function is achieved.
In this embodiment, the intermediate non-isolated DC-DC converting circuit 5 is a single-phase non-isolated DC-DC converting circuit. The intermediate non-isolated DC-DC converting circuit 5 comprises a second inductor L2, a second switching circuit 51, a second diode D2 (a second rectifier element), and a pulse width modulation controller 52. A first terminal of the second inductor L2 is connected with the input terminal of the intermediate non-isolated DC-DC converting circuit 5. A second terminal of the second inductor L2 is connected with a second connecting node K2. The second switching circuit 51 is connected between the second connecting node K2 and the common terminal COM. The anode of the second diode D2 is connected with the second connecting node K2. The cathode of the second diode D2 is connected with the output terminal of the intermediate non-isolated DC-DC converting circuit 5. The pulse width modulation controller 52 is connected with the common terminal COM and the control terminal of the second switching circuit 51 for controlling operations of the second switching circuit 51. Consequently, the bus voltage Vbys is converted into the intermediate output voltage Vi by the intermediate non-isolated DC-DC converting circuit 5.
In this embodiment, the non-isolated DC-DC converting circuit 6 is a single-phase non-isolated DC-DC converting circuit. The non-isolated DC-DC converting circuit 6 comprises a third inductor L3, a third diode D3 (a third rectifier element), a first output capacitor Co1, a third switching circuit 61 and a DC-DC controlling unit 62. The third inductor L3 is connected between the third connecting node K3 and the output terminal of the non-isolated DC-DC converting circuit 6. The third diode D3 is connected between the third connecting node K3 and the common terminal COM. The first output capacitor Co1 is connected between the non-isolated DC-DC converting circuit 6 and the common terminal COM. The third switching circuit 61 is connected between the input terminal of the non-isolated DC-DC converting circuit 6 and the third connecting node K3. The DC-DC controlling unit 62 is connected with the control terminal of the third switching circuit 61, the common terminal COM and the high-voltage battery unit 2. According to the high charging voltage VHb, the on/off statuses of the third switching circuit 61 are controlled by the DC-DC controlling unit 62.
In this embodiment, the DC-DC controlling unit 62 comprises a second feedback circuit 621 and a DC-DC controller 622. The second feedback circuit 621 is connected to the high-voltage battery unit 2, the DC-DC controller 622 and the common terminal COM. The second feedback circuit 621 is used for performing voltage division on the high charging voltage VHb, thereby generating a second feedback signal Vf2. The DC-DC controller 622 is connected to the control terminal of the third switching circuit 61, the second feedback circuit 621 and the common terminal COM. According to the second feedback signal Vf2, the DC-DC controller 622 judges whether the high charging voltage VHb is maintained at the rated voltage value (e.g. 400V). As a consequence, the duty cycle of the third switching circuit 61 is controlled, and the high charging voltage VHb is maintained at the rated voltage value.
The electric energy path of the non-isolated DC-DC converting circuit 6 is transmitted through the third switching circuit 61 and the third inductor L3. In other words, no transformer is included in the non-isolated DC-DC converting circuit 6. In the non-isolated DC-DC converting circuit 6, a first output filter circuit is defined by the third inductor L3 and the first output capacitor Co1. The operations of the first output filter circuit and the third switching circuit 61 cause the high-voltage battery unit 2 to be charged by the high charging voltage VHb. That is, by the switching circuit and the output filter circuit of the non-isolated DC-DC converting circuit 6, the high-voltage battery unit 2 is charged by the high charging voltage VHb.
In the above embodiments, the rectifier circuit 3 is a bridge rectifier circuit. The positive output terminal of the rectifier circuit 3 is connected to the input terminal of the power factor correction circuit 4. The negative output terminal of the rectifier circuit 3 is connected to the common terminal COM. An example of the first current-detecting circuit 42 includes but is not limited to a current transformer or a detecting resistor R. Each of the first switching circuit 41, the second switching circuit 51 and the third switching circuit 61 includes one or more switch elements. The switch element is a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT) or an insulated gate bipolar transistor (IGBT). In a preferred embodiment, each of the first switching circuit 41, the second switching circuit 51 and the third switching circuit 61 includes a metal oxide semiconductor field effect transistor (MOSFET). Moreover, each of the power factor correction controller 433 and the DC-DC controller 622 includes a controller, a micro controller unit (MCU) or a digital signal processor (DSP).
When the AC input voltage Vin is received by the high-voltage battery charging system and the low-voltage battery unit 22 needs to be charged, the user may trigger the starting unit 24 to have the starting unit 24 issue a starting signal Vs1. The auxiliary controlling unit 23 is connected with the starting unit 24, the auxiliary power circuit 20, the low-voltage battery unit 22 and the control terminal of the charge switching circuit 25. The auxiliary controlling unit 23 is powered by the low voltage V1v. Moreover, the auxiliary controlling unit 23 is used for controlling operations of the auxiliary power circuit 20. Depending on the condition whether the starting signal Vs1 is received or not, the auxiliary controlling unit 23 controls the on/off statuses of the charge switching circuit 25. The low-voltage power circuit 21 is connected with the output terminal of the power factor correction circuit 4 and the common terminal COM. The low-voltage power circuit 21 is used for receiving the bus voltage Vbus and converting the bus voltage Vbus into a low charging voltage V1vd (e.g. 12V). The low charging voltage V1vd may be used to power the components of the electric vehicle that are enabled by low voltage. The charge switching circuit 25 is connected between the low-voltage battery unit 22 and the output terminal of the low-voltage power circuit 21. Under control of the auxiliary controlling unit 23, the charge switching circuit 25 is selectively conducted or shut off. In a case that the charge switching circuit 25 is conducted, the low charging voltage V1vd is transmitted from the low-voltage power circuit 21 to the low-voltage battery unit 22 through the charge switching circuit 25, thereby charging the low-voltage battery unit 22.
From the above descriptions, when the AC input voltage Vin is received by the high-voltage battery charging system and the low-voltage battery unit 22 needs to be charged, the user may trigger the starting unit 24 to have the starting unit 24 issue a starting signal Vs1. In response to the starting signal Vs1, the charge switching circuit 25 is conducted under control of the auxiliary controlling unit 23. Consequently, the low charging voltage V1vd is transmitted from the low-voltage power circuit 21 to the low-voltage battery unit 22 through the charge switching circuit 25, thereby charging the low-voltage battery unit 22.
In some embodiments, the bus capacitor Cbus is replaceable.
The bus capacitor module 33 is replaceable, and fixed on the partition plate assembly 32 by a screwing means. The second connecting part 314 is detachably connected with the first connecting part 311. The bus capacitor Cbus comprises at least one electrolytic capacitor. Moreover, the bus capacitor Cbus may be welded on the supporting plate 312. The supporting plate 312 may be fixed on the partition plate assembly 32 by a screwing means. The second connecting part 314 is fixed on the supporting plate 312 by a fastening element 315. The fastening element 315 is made of conductive material. In addition, the fastening element 315 is inserted in the supporting plate 312. Through a trace pattern or a conductor line on the supporting plate 312, the fastening element 315 is electrically connected with the bus capacitor Cbus. Consequently, the second connecting part 314 is electrically connected with the bus capacitor Cbus through the fastening element 315. The supporting plate 312 is covered with the covering member 313 by fastening means, so that the bus capacitor Cbus is sheltered by the covering member 313. In some embodiments, the covering member 313 has the same number of slots 316 as the number of the electrolytic capacitors of the bus capacitor Cbus. After the supporting plate 312 is covered with the covering member 313, the slots 316 may partially accommodate corresponding electrolytic capacitors, thereby facilitating fixing the electrolytic capacitors.
As can be seen from
From the above descriptions, the present invention provides a high-voltage battery charging system for use in an electric vehicle and also a charger with such a high-voltage battery charging system. Due to the intermediate non-isolated DC-DC converting circuit, the intermediate output capacitor connected with the input terminal of the non-isolated DC-DC converting circuit has a higher rated voltage value. Consequently, the non-isolated DC-DC converting circuit will generate a wide range of the high charging voltage. Moreover, the auxiliary power circuit is powered by the low-voltage battery unit. Consequently, if the AC input voltage received by the high-voltage battery charging system is abnormal or interrupted, the auxiliary power circuit is normally operated to continuously deliver electric energy to various controlling units. Under this circumstance, since the functions of various controlling units of the electric vehicle can be continuously maintained, the reliability of the high-voltage battery charging system is enhanced. Moreover, the bus capacitor used in the high-voltage battery charging system of the present invention is replaceable. After the bus capacitor has been used for a long time period, the bus capacitor may be replaced with a new one without the need of changing the whole charger. In other words, the use of the charger of the present invention has good replacing convenience and is resource-saving.
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201110314943.8 | Oct 2011 | CN | national |
