阅读说明：本技术 使用一个ac/dc转换器实现用于电动车辆的快速电池充电和马达驱动的装置 (Apparatus for implementing fast battery charging and motor driving for electric vehicle using one AC/DC converter ) 是由 A.W.布朗 H.白 于 2018-03-23 设计创作，主要内容包括：一种装置包括控制器、开关块和三相双向AC/DC转换器。开关块具有连接到电力网的第一接口、连接到电动马达的第二接口以及连接到三相双向AC/DC转换器的第三接口,所述三相双向AC/DC转换器包括第一、第二和第三单相AC/DC转换模块,并且所述三相双向AC/DC转换器具有在输出节点处接合的输入和输出以及被配置成提供电隔离的相应变压器。在第一操作模式中,开关块使电力网连接到AC/DC转换器以用于对连接到输出节点的电池充电,并且断开电动马达。在第二操作模式中,开关块断开电力网,并且将电动马达连接到AC/DC转换器,所述AC/DC转换器被控制以转换从电池汲取的DC功率来激励电动马达。(an apparatus includes a controller, a switch block, and a three-phase bidirectional AC/DC converter. The switch block has a first interface connected to a power grid, a second interface connected to an electric motor, and a third interface connected to a three-phase bidirectional AC/DC converter that includes first, second, and third single-phase AC/DC conversion modules, and has an input and an output joined at an output node and a respective transformer configured to provide electrical isolation. In a first mode of operation, the switching block connects the power grid to the AC/DC converter for charging a battery connected to the output node and disconnects the electric motor. In a second mode of operation, the switching block disconnects the power grid and connects the electric motor to an AC/DC converter that is controlled to convert DC power drawn from the battery to energize the electric motor.)

1. An electric power conversion device comprising:

An electronic controller comprising a processor and a memory;

A switch block controlled by the controller and having a first interface configured to connect to a power grid source for receiving a first AC signal having first, second and third phases, the switch block having a second interface configured to connect to an electric motor;

A three-phase bidirectional AC/DC converter configured to be connected to a third interface of the switch block and including first, second, and third single-phase AC/DC conversion modules each connected to and controlled by the controller, the AC/DC conversion modules having respective inputs, respective outputs joined at an output node, and respective transformers configured to provide electrical isolation;

wherein in a first mode of operation, the controller controls the switch block to assume a first state that (i) connects the first interface and the third interface such that the power grid is connected to the three-phase AC/DC converter, the three-phase AC/DC converter being controlled to convert the first AC signal into an output signal having a DC component at the output node for charging a battery, and (ii) disconnects the second interface and the third interface to thereby disconnect the electric motor; and is

Wherein in a second mode of operation, the controller controls the switch block to assume a second state that (i) disconnects the first interface and the third interface in order to disconnect the power grid, and (ii) connects the second interface and the third interface to connect the electric motor to the three-phase bidirectional AC/DC converter, which is controlled to convert DC power drawn from the battery into a second AC signal for energizing the electric motor.

2. The apparatus of claim 1, further comprising operating mode control logic stored in the memory and configured, when executed by the controller, to control the switch block to assume (i) the first state when predetermined battery charging criteria are met and (ii) the second state when predetermined motor drive criteria are met.

3. The apparatus of claim 1, further comprising master control logic stored in the memory that, when executed by the controller, is configured to: when in the first mode of operation, controlling operation of the three-phase bidirectional AC/DC converter to achieve Power Factor Correction (PFC) and Zero Voltage Switching (ZVS) while charging the battery.

4. The apparatus of claim 1, wherein each AC/DC conversion module respectively includes (i) a rectifier stage for converting a respective phase of the first AC signal to a DC signal, and (ii) a Dual Active Bridge (DAB) stage configured to convert the DC signal to the output signal having the DC component.

5. The apparatus of claim 4, wherein operation of the first, second and third AC/DC conversion modules produces their respective AC components that tend to cancel each other out in the first mode of operation.

6. The apparatus of claim 4, wherein each rectifier stage is coupled to a respective one of the first, second, and third phases of the first AC signal and configured to generate a respective DC signal, each rectifier stage comprising a respective plurality of rectifier switches arranged in a full-bridge arrangement.

7. The apparatus of claim 6, wherein the controller comprises rectifier logic stored in the memory, the rectifier logic, when executed by the controller, configured to generate a first set of switch control signals corresponding to gate drive signals of the plurality of rectifier switches.

8. The apparatus of claim 7, further comprising a grid voltage sensor in sensory association with the first AC signal from the power grid source, the grid voltage sensor configured to generate a grid voltage signal indicative of the first AC signal voltage.

9. The apparatus of claim 8, wherein in the first mode of operation, the rectifier logic is responsive to the grid voltage signal in generating the first set of switch control signals to provide synchronous rectification of the first AC signal.

10. The apparatus of claim 7, wherein in the second mode of operation, the rectifier logic is configured to control the rectifier stage to generate the second AC signal for the electric motor according to a motor fundamental frequency.

11. The apparatus of claim 4, wherein each Dual Active Bridge (DAB) stage comprises:

(i) a first full bridge coupled to the rectifier stage, comprising a plurality of DC-to-AC switches,

(ii) The transformer having respective primary windings coupled to the first full bridge, the transformer having electrically isolated and magnetically coupled secondary windings, an

(iii) A second full bridge between the secondary winding and the output node and comprising a plurality of AC to DC switches.

12. The apparatus of claim 11, further comprising a coupling inductor in series between the first full bridge and the primary winding of the transformer.

13. The apparatus of claim 11, wherein the first AC signal has a first frequency, the first full bridge configured to: in the first mode of operation, convert the first DC signal to a third AC signal, the third AC signal having a second frequency greater than the first frequency, the main control logic, when executed by the controller in the first mode of operation, configured to generate (i) a second set of switch control signals corresponding to gate drive signals for the plurality of DC to AC switches and (ii) a third set of switch control signals corresponding to gate drive signals for the AC to DC switches.

14. The apparatus of claim 13, wherein the main control logic comprises Power Factor Correction (PFC) logic configured to generate the second and third sets of switch control signals to increase a power factor associated with power drawn from the power grid source toward one when executed by the controller in the first mode.

15. The apparatus of claim 14, wherein the PFC logic is configured to vary a phase difference in gate drive signals associated with respective DAB stages.

16. The apparatus of claim 4, wherein the main control logic comprises motor control logic stored in the memory, the motor control logic, when executed by the controller in the second mode of operation, configured to control operation of the first, second, and third AC/DC conversion modules based on motor control command signals to generate the second AC signal to drive the electric motor.

17. The apparatus of claim 1, wherein the switch block comprises an electrically actuated relay.

18. The apparatus of claim 1, further comprising master control logic stored in the memory that, when executed by the controller, is configured to: when in the second mode of operation, controlling operation of the three-phase bidirectional AC/DC converter so as to achieve Zero Voltage Switching (ZVS) while driving the motor.

19. An electric power conversion apparatus for charging a battery and driving an electric motor, comprising:

An electronic controller comprising a processor and a memory;

A switch block controlled by the electronic controller and having a first interface configured to be electrically connected to a power grid for receiving a first AC electrical signal having first, second and third phases, the switch block having a second interface configured to be connected to an electric motor;

A three-phase bidirectional AC/DC converter configured to be electrically connected to the third interface of the switch block and including first, second and third single-phase AC/DC conversion modules each connected to and controlled by the electronic controller, the AC/DC conversion modules having respective inputs, respective outputs joined at an output node, and respective transformers configured to provide electrical isolation;

Wherein in a first mode of operation, the controller controls the switch block to assume a first state that (i) electrically connects the first interface and the third interface so as to connect the power grid to the three-phase bidirectional AC/DC converter, the three-phase bidirectional AC/DC converter being controlled to convert the first, AC electrical input signal into an output signal having a DC component at the output node for charging a rechargeable battery connected to the output node, and (ii) electrically disconnects the second interface and the third interface to thereby electrically disconnect the electric motor; and also

Wherein in a second mode of operation, the controller controls the switch block to assume a second state that (i) electrically disconnects the first interface and the third interface in order to disconnect the power grid, and (ii) electrically connects the second interface and the third interface to thereby electrically connect the electric motor to the three-phase bidirectional AC/DC converter, which is controlled to convert DC power drawn from the battery into a second AC electrical signal for energizing the electric motor.

Technical Field

The present disclosure relates generally to power electronics systems, and more particularly to systems and methods for implementing fast battery charging and motoring, for example, for electric vehicles, using one AC/DC converter.

background

This background description is set forth below for the purpose of providing a context only. Thus, any aspect described in this background is neither expressly nor impliedly admitted as prior art against the present disclosure in so far as it is not otherwise known as prior art.

Isolated Alternating Current (AC)/Direct Current (DC) electrical power converters may be used in many different applications. For example only, such an electrical power converter may draw power (i.e., AC power) from the grid or power line and be used as a battery charger to charge a DC rechargeable battery associated with an electric motor-powered motor vehicle. In electric motor powered vehicles, the power electronic converter is the most economically expensive part in addition to the battery pack (e.g., DC rechargeable battery). As the two main power electronic converters, the battery charger (i.e., the AC/DC converter) and the electric motor drive system (i.e., the DC/AC inverter) are typically separate units, even though they share the same battery pack. For charger designs, electrical isolation between the grid and the battery requires the presence of transformers and inductors, which leads to the case where the battery charger is the largest piece (i.e., volume occupied) of power electronics in or on the electric motor powered vehicle. For a DC/AC inverter, the DC bus capacitor in parallel with the battery is also typically bulky and heavy, occupying 1/3 of the potential overall inverter space.

It would be desirable to provide a system and method for performing at least two of the above-described functions of battery pack charging and motor driving that minimizes and/or eliminates at least one or more of the above-described disadvantages and/or problems.

The foregoing discussion is intended to be merely illustrative of the art and should not be considered a disclaimer of the scope of the claims.

Disclosure of Invention

In an embodiment, an electrical power conversion device is provided that includes an electronic controller including a processor and a memory, a switching block, and a three-phase bidirectional AC/DC converter. The switch block is controlled by a controller and has a first interface configured to be connected to a power grid source for receiving a first AC signal having first, second and third phases (electrical phases). The switch block has a second interface configured to connect to the electric motor. The three-phase bidirectional AC/DC converter is configured to be connected to a third interface of the switch block and includes first, second, and third single-phase AC/DC conversion modules. Each AC/DC conversion module is connected to and controlled by the controller. In an embodiment, each single-phase AC/DC conversion module has a respective input configured to be connected to a respective phase of a first AC signal having first, second, and third phases. The AC/DC conversion module also has respective outputs joined at an output node and having respective transformers configured to provide electrical isolation.

In a first mode of operation, the controller controls the switch block to assume a first state that (i) connects the first and third interfaces such that the power grid is connected to a three-phase bidirectional AC/DC converter operable to convert a first three-phase AC signal to an output signal having a DC component at an output node for charging the battery. In the first mode, the switch block disconnects the second and third interfaces to thereby disconnect the electric motor.

In a second mode of operation, the controller controls the switch block to assume a second state that (i) disconnects the first and third interfaces in order to disconnect the power grid, and (ii) connects the second and third interfaces to thereby connect the electric motor to a three-phase bidirectional AC/DC converter operable to convert DC power drawn from the battery into a second AC signal for energizing the electric motor. In an embodiment, the apparatus may be used as a battery charger to charge a DC rechargeable battery (e.g., associated with an electric motor-powered motor vehicle) and as an electric motor capable of being used as an inverter to drive the motor vehicle.

With the foregoing in mind, embodiments in accordance with the present disclosure provide an improved electrical power conversion device that uses a single bidirectional AC/DC converter to achieve both fast battery charging and electric motor drive, which reduces cost, reduces bulkiness (which increases power density), improves efficiency, and facilitates fast charging.

The foregoing and other aspects, features, details, utilities, and advantages of the present disclosure will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.

Drawings

Fig. 1 is a schematic and block diagram of an electric power conversion apparatus using a single bidirectional AC/DC converter according to an embodiment.

Fig. 2 shows a first power flow in a first mode of operation of the apparatus of fig. 1 for charging a rechargeable battery from grid power.

Fig. 3 shows a second power flow (AC power) in a second mode of operation of the apparatus of fig. 1 for driving an electric motor from DC power drawn from a battery.

Fig. 4 is a simplified schematic and block diagram illustrating the bidirectional AC/DC converter of fig. 1-3 in more detail and having a respective AC/DC conversion module for each of the first, second and third phases of the AC grid power signal.

Fig. 5 is a schematic, schematic and block diagram illustrating one of the AC/DC power conversion modules shown in block form in fig. 4 in greater detail in an embodiment.

Fig. 6 shows a simplified timing diagram of a first set of switch control signals associated with the full bridge AC/DC rectifier of fig. 5.

Fig. 7 shows a simplified timing diagram of the second and third sets of switch control signals that control the operation of the dual active bridge of fig. 5.

Fig. 8 is a timing diagram of parameters for determining the switching timing of fig. 7.

Fig. 9 shows the load side (battery) current and voltage output from the embodiment of fig. 5 in a first (charging) mode of operation.

Fig. 10 is a simplified schematic and block diagram of the apparatus of fig. 1 in a further embodiment in a second mode of operation for electric motor drive.

Detailed Description

Various embodiments are described herein for various apparatuses, systems, and/or methods. Numerous specific details are set forth in order to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. However, it will be understood by those skilled in the art that embodiments may be practiced without such specific details. In other instances, well-known operations, components and elements have not been described in detail so as not to obscure the embodiments described in the specification. It will be appreciated by persons of ordinary skill in the art that the embodiments described and illustrated herein are non-limiting examples, and thus it is to be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, which are defined solely by the appended claims.

Reference throughout the specification to "various embodiments," "some embodiments," "one embodiment," or "an embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," or "in an embodiment," or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, a particular feature, structure, or characteristic illustrated or described in connection with one embodiment may be combined, in whole or in part, with a feature, structure, or characteristic of one or more other embodiments without limitation, as long as such combination is not illogical or functional.

Referring now to the drawings, wherein like reference numerals are used to identify the same or similar components in the various views, fig. 1 is a simplified schematic and block diagram of an embodiment of an electrical power conversion device 10 according to the present disclosure that uses one bi-directional AC/DC converter 18 to achieve both battery charging (e.g., high power fast battery charging) and electric motor drive functions. Fig. 1 represents an equivalent circuit of an embodiment and shows an Alternating Current (AC) input power source 12, an electric motor 14, a switching block 16, a bidirectional AC/DC converter 18, and a rechargeable DC battery 20.

The AC source 12 may be a main AC power source or electrical system for a building or the like provided throughout a larger AC power grid (sometimes referred to hereinafter as grid power, grid voltage, grid side, etc.). As shown, the AC source 12 may be multiple phases (e.g., three phases: phase A, phase B, phase C). Depending on the location, the AC source 12 may output 208/480V AC3 phase at 60Hz or 380 phase at 50 Hz480V AC3 phase. Voltage V of battery 20_bMay be nominally between about 200-500V DC (e.g., 400V DC). However, it should be understood that lower or higher DC battery voltage levels now known or later developed may be employed in accordance with the present teachings.

The electric motor 14 may be any conventional electric motor suitable for use in, by way of example only, an electric motor in an electric motor vehicle powered by the electric motor. In an embodiment, the motor 14 may include a Permanent Magnet Synchronous Motor (PMSM) as controlled by an electronic controller (e.g., controller 46 — fig. 5) as described in more detail below in connection with fig. 10.

The switch block 16 is also controlled by a controller (e.g., controller 46-fig. 5) and may be functionally represented as a first electrical relay group 16₁And a second electrical relay group 16₂. The switch block 16 includes a first interface 22 configured to be electrically connected to the AC power source 12 for receiving a first (grid) AC power signal having first, second, and third electrical phases (e.g., each phase is offset by 120 degrees). First interface 22 as shown may include three separate electrical connections corresponding to three phases of an AC input signal from grid source 12. The switch block 16 also includes a second interface 24 configured to be electrically connected to the electric motor 14. The second interface 24 also includes three electrical connections corresponding to three of the AC drive signals that drive (energize) the electric motor 14. The switch block 16 also includes a third interface 26 configured to electrically connect to the bi-directional AC/DC converter 18. As shown, the third interface 26 includes data from the relay bank 16₁And 16₂Although in the illustrated embodiment, from the relay bank 16₁And 16₂The respective connections of each are electrically connected (joined), resulting in three connections to the bidirectional AC/DC converter 18.

In an embodiment, a corresponding relay group 16₁And 16₂As two three-phase switch operations, group 16₁For AC grid connection, and group 16₂For electric motor connection. Additionally, group 16₁And 16₂Controlled to be complementaryThe method operates. Thus, when charging the vehicle, the cluster 16₁Are closed and group 16 is₂The connection of (2) is broken. Also, when the motor is driven, the group 16₁Is disconnected, and group 16₂The connection of (2) is closed. The switch block 16 may include electrical switches, relays, solid state switches, and other conventional devices configured to open and close electrical connections. In an embodiment, a hardware implementation may be selected to implement the complementary operations, such as by using a Double Pole Double Throw (DPDT) switch or its equivalent (i.e., only one, but not both, of the AC grid connection and the electric motor connection may be closed at any time).

The bi-directional AC/DC converter 18 is generally configured to operate in two modes. In the first mode, the converter 18 is operable to convert an input three-phase AC signal from the AC power source 12 into an output signal having a predominant DC component on the output node 80 for the purpose of charging or recharging the battery 20. In the second mode of operation, the converter 18 is operable to convert DC power drawn from the battery 20 into an output three-phase electrical signal for driving (energizing) the electric motor 14. As will be described in more detail below, the converter 18 includes a plurality of transformers (e.g., one per phase) configured to provide electrical isolation between the grid and the battery and between the battery and the electric motor.

Fig. 2-3 illustrate the device 10 in a first charging mode of operation and a second motoring mode of operation, respectively.

In the first mode of operation (fig. 2), the controller (e.g., controller 46 — fig. 5) controls the switch block 16 to assume a first state in which the switch block 16 electrically connects the first interface 22 and the third interface 26 such that the first three-phase AC grid power signal from the source (grid) 12 is electrically connected to the bidirectional AC/DC converter 18. The converter 18, in turn, is operable, under control of the controller, to convert the three-phase AC input signal into an output signal (primarily a DC component) for charging the battery 20. Meanwhile, in the first mode, the switch block 16 in the first state electrically disconnects the second interface 24 from the third interface 26 to thereby electrically disconnect the electric motor 14. As shown in fig. 2, as indicated by the reference numeralsElectrical power flows from the AC mains power supply 12 to the battery 20 as indicated by numeral 28. In a representative manner, group 16₁Is electrically closed, and the group 16₂Is electrically disconnected.

In the second mode of operation (fig. 3), the controller (e.g., controller 46 — fig. 5) controls the switch block 16 to assume a second state in which the switch block 16 electrically disconnects the first interface 22 and the third interface 26 in order to electrically disconnect the AC grid power source 12. While in the second mode, the switch block 16 in the second state electrically connects the second interface 24 to the third interface 26 to thereby electrically connect the electric motor 14 to the bi-directional AC/DC converter 18. The converter 18 is in turn controlled by the controller to convert the DC power drawn from the battery 20 into a second three-phase AC signal suitable for driving or electrically exciting the electric motor 14. As shown in fig. 3, power flows from the battery 20 to the electric motor 14, as indicated by reference numeral 30. In a representative manner, group 16₁Is electrically disconnected, and the group 16₂Is electrically closed.

Embodiments in accordance with the present disclosure have many advantages including the following.

Low cost. Using one AC/DC converter to achieve both rapid charging and motoring results in a significant cost reduction of the overall power electronics system on the electric vehicle compared to conventional implementations that include separate AC/DC and DC/AC converters for charging and driving functions.

High power density. In an embodiment, the bidirectional AC/DC converter employs GaN HEMT solid-state switches in the switching module (more below) that can operate at relatively high switching frequencies > 100 kHz, which can be almost ten times as fast as the switching frequencies associated with conventional Si switches. Such high switching frequencies result in higher order harmonics that are more easily filtered. This situation therefore allows the use of a much smaller output capacitor in parallel with the battery.

High efficiency. Conventional DC/AC inverters operate in hard switching mode, which results in high switching losses and thus low switching frequencies. In an embodiment, bidirectional AC/DC conversionThe converter is configured to operate in a soft switching mode, resulting in higher efficiency. In contrast, a conventional Si switch-based inverter may have a switching frequency of 10 kHz and 96% efficiency, while a GaN HEMT switch-based inverter embodiment has a switching frequency > 100 kHz and 98% efficiency, even with an isolation transformer.

Facilitating fast charging. In conventional battery chargers, their power capacity is limited not only by the power of the grid, but also by their cost and the amount of available space. In the case of many single-phase chargers having a power density of about 1 kW/L and three-phase chargers having a power density of about 2 kW/L, it is difficult to design a charger with a power capacity of > 20 kW, which would require significant space (volume) in the vehicle in order to achieve it. However, by using the same converter for both battery charging and motor driving purposes, the charger and inverter will have the same power level, which makes the system particularly suitable for so-calledFast speedIn a (high power) battery charging method, the method has, for example, a power capacity in the range of 50 kW.

Fig. 4 is a simplified schematic and block diagram illustrating the topology of an embodiment of the bidirectional AC/DC converter 18 of fig. 1. In an embodiment, the converter 18 includes first, second and third single-phase AC/DC conversion modules designated by reference numerals 32A, 32B and 32C in fig. 4. Each of conversion modules 32A, 32B, and 32C has a respective input electrically connected to one of phase a, phase B, and phase C of the AC grid power signal from grid source 12. As further shown, the conversion modules 32A, 32B, and 32C have outputs electrically coupled between the output node 80 and the common ground node 82. Each of the conversion modules 32A, 32B, and 32C is also connected to a controller (e.g., controller 46-FIG. 5), which controls the operation of the modules.

Each conversion module 32A, 32B, and 32C also includes a respective transformer that provides electrical isolation between the grid and the battery 20 when charging the battery 20. Additionally, however, when driving the motor 14, the converter 18, operating as an inverter, also inherits the electrical isolation and transformer it provides between the battery 20 and the motor 14. However, since the transformer operates at a much higher switching frequency (below), its size will be much smaller than conventional. Thus, the transformer will not be a disadvantage when operating in the second, electrically driven mode of operation.

fig. 5 is a simplified schematic and block diagram illustrating one of the AC/DC conversion modules of fig. 4 in greater detail, along with a controller 46 that controls its operation. As shown, an AC/DC conversion module (designated 32)_iWhereiniWhich may be one of phases A, B or C) is coupled to a corresponding one of the phases of the AC mains power supply 12. In this context, a single phase AC signal is provided on the input node 36 as shown. Conversion module 32_iAn input inductor 34 may be included, electrically coupled in series with the AC source, configured to smooth the grid-side current. The size of the inductor 34 will depend on the degree of smoothing and the switching frequency. In an embodiment, inductor 34 may be approximately 10 microhenries (μ H). Conversion module 32_iAnd is also configured to output a DC voltage signal on output node 80.

Each single-phase conversion module 32_iIncluding respective rectifier stages 66 and respective Dual Active Bridge (DAB) stages. The DAB stage comprises (i) a first full bridge 68, (ii) a transformer 40 and (iii) a second full bridge 70.

Rectifier stage 66 (AC/DC converter) constitutes a means for rectifying the first AC input signal at node 36 and producing a first rectified output signal at node 38 with respect to ground node 39. The first rectified signal includes a first Direct Current (DC) component. The rectifier stage 66 may include four semiconductor switches (designated as M1, M2, M3, M4) operating at a grid frequency (e.g., 50/60 Hz) and arranged in a full bridge configuration when operating in a first (charging) mode of operation. When operating in the second (motoring) mode of operation, the rectifier stage 66 may operate at an electric motor frequency (e.g., fundamental).

The switches M1, M2, M3, M4 may comprise conventional semiconductor switches known in the art, such as MOSFET or IGBT devices. In an embodiment, switches M1, M2, M3, M4 may comprise Si N channel power MOSFETs provided under the trade name and/or part number STY139N65M5 from STMicroelectronics, Coppell, texas, usa.

conversion module 32_iMay also include a capacitor C_inWhich is connected across the output of rectifier stage 66 between node 38 and ground node 39. Capacitor C_inDimensionally configured to filter high frequency harmonics (e.g., relatively small:. mu.F order) from the rectified signal at node 38. It should be understood that C_inNot for energy storage but for filtering purposes and is therefore not a large, bulk DC bus capacitor, where the DC bus capacitor may be on the order of millifarads (mF). C_inThis reduced size of (a) may also increase power density and extend service life.

A first full bridge 68 (i.e., DC/AC converter 68) is electrically connected to the outputs of the rectifier stage 66 (i.e., connected across nodes 38, 39) and is configured to convert the first DC (rectified) signal on node 38 to a relatively high frequency AC signal. As illustrated, the bridge 68 may include four semiconductor switches (designated as P1, P2, P3, P4) and is arranged at a second frequency (i.e., switching frequency f)_s) A full bridge configuration of operation. Second, switching frequency f_sTypically much higher than the first, grid frequency. In an embodiment, the second, switching frequency may be in the range between about 135 kHz to 500 kHz, while the first, grid frequency may be 60Hz (or 50 Hz). The semiconductor switches P1, P2, P3, P4 may comprise commercially available components known in the art. In an embodiment, the switches P1, P2, P3, P4 may include commercially available wide bandgap components, such as, for example, 650V GaN High Electron Mobility Transistor (HEMT) devices, enhancement mode GaN transistors such as those provided under the brand name and/or part number GS66516T from GaN Systems, inc.

The first and second full bridges 68, 70 of the Dual Active Bridge (DAB) are electrically isolated but (magnetically) coupled by the transformer 40 having the primary winding 42 and the secondary winding 44. The first full bridge 68 is formed by a series inductor L_pIs electrically connected to the primary winding 42. Collar of collarWill be that the series inductor L_pEither a built-in leakage inductance in the transformer or an external inductance placed in series with the transformer. Inductor L_pCan be used to store energy to achieve Zero Voltage Switching (ZVS) across the primary and secondary full bridge semiconductors during high frequency switching processes. Additionally, as is known, the transformer 40 is characterized by a turns ratio between the secondary winding and the primary winding.

A second full bridge 70 (i.e., AC/DC converter 70) is electrically connected to the second winding 44 of the transformer 40 and is configured to convert or rectify the AC signal induced on the secondary winding 44 into a second rectified output signal on output node 80. From a single-phase conversion device 32_iHas a DC component and at least one AC component, wherein the at least one AC component includes a second order harmonic of the grid frequency (e.g., a 120 Hz component for a 60Hz grid frequency). And each single-phase module 32_iCorresponding 120 Hz ripple signals will be generated, the combination of these individual ripple signals will tend to cancel each other out by virtue of the phase difference between them, thereby becoming neutralized when used in three-phase mode (charging mode). This is shown in fig. 9, where the reduced ripple output current is shown in trace 84 and the reduced ripple output voltage (referenced to the output voltage of a nominal 400 volt battery) is shown in trace 86.

In the illustrated embodiment, the second full bridge 70 (AC/DC converter 70) may include four semiconductor switches (designated as switch S)₁、S₂、S₃、S₄) Arranged in an active H-bridge (full-bridge) switch arrangement. In an embodiment, the switching arrangement 70 is controlled to have the above-mentioned switching frequency f_sOperation (i.e. switch S)₁～S₈Controlled to have the same switching frequency f_sOperation). Semiconductor switch S₁、S₂、S₃、S₄Commercially available components may be included, such as 650V GaN High Electron Mobility Transistor (HEMT) devices, such as the enhanced G provided under the brand name and/or part number GS66516T from GaN Systems, Inc. of Ann arbor, MichaN transistor.

Fig. 5 also shows a C designation connected across output node 80 and ground node 82 and dimensionally configured to filter high frequency harmonics from the output signal at node 80₀E.g., relatively small: -uF stage). In the embodiment, the capacitor C₀may be about 100 muf.

Also shown in FIG. 5 is an electronic control unit 46 (hereinafter controller 46) configured to implement a desired control strategy for operation of the apparatus 10, including the AC/DC conversion module 32_iEach of which. It should be understood that although the controller 46 is shown as having an input/output associated with one AC/DC conversion module, the controller 46 may be configured to control all of the AC/DC conversion modules, or alternatively, additional controllers 46 may be provided.

The controller 46 includes an electronic processor 48 and a memory 50. Processor 48 may include processing capabilities and an input/output (I/O) interface through which processor 48 may receive a plurality of input signals and generate a plurality of output signals (e.g., for switch M)₁～M₄、P₁～P₄、S₁～S₄the gate driving signal). Memory 50 is provided for storing data and instructions or code (i.e., software) for processor 48. The memory 50 may include various forms of non-volatile (i.e., non-transitory) memory, including flash memory or Read Only Memory (ROM), including various forms of programmable read only memory (e.g., PROM, EPROM, EEPROM), and/or volatile memory, including Random Access Memory (RAM) including Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), and Synchronous Dynamic Random Access Memory (SDRAM). Although not shown in FIG. 5, the conversion module 32_iA driver circuit may also be included to interface between the output of the controller 46 and the gate terminal of the semiconductor switch. In embodiments, such gate drive devices may comprise commercially available components, such as those known in the artFor example, a gate driving chip available under part number IXD _614 from IXYS corporation of Milpitas, california, usa.

The memory 50 also stores executable code in the form of master control logic 51 configured to control the overall operation of the apparatus 10 in accordance with a desired control strategy. When executed by the processor 48, the main control logic 51 is configured to generate a signal for the switch M in response to one or more input signals₁～M₄、P₁～P₄And S₁～S₄Various gate drive signals. The main control logic 51 may include programmed logic blocks for implementing specific functions, including but not limited to grid rectifier logic 58, Power Factor Correction (PFC) logic 60, Zero Voltage Switching (ZVS) logic 62, and operating mode control logic 64.

Grid rectifier logic 58 is configured to generate switch M for rectifier stage 66₁～M₄The gate driving signal of (1). To accomplish this, the apparatus 10 may include a respective grid voltage sensor 52 (shown in block form — one block for each conversion module) configured to output a respective signal indicative of the grid voltage, including polarity (i.e., positive or negative). Voltage sensors 52 may be disposed on the grid side (i.e., electrically connected to respective phases of AC source 12) to monitor the grid voltage. In an embodiment, the sensor 52 may include conventional components known in the art.

Fig. 6 shows a timing diagram of the gate drive signals (i.e., switch control signals) generated by the gate rectifier logic 58 of the controller 46. In a first (charging) mode of operation, based on M₁～M₄Will rectify the grid AC voltage to a DC voltage. In the examples, M₁～M₄The switching frequency of (2) is the same as the grid voltage (e.g., 50-60 Hz). Note that M₁～M₄The control is carried out by detecting the polarity of the network voltage. Thus, when the grid voltage is positive, M₁And M₄Is turned on (i.e., M)₁And M₄V of_GSHigh). When the grid voltage is negative, M₂And M₃And (4) switching on. Switch M₁and M₄The gate drive signals of (a) are operated in unison, and the switch (M) is operated₂And M₃Operate in unison. Additionally, M₁M₄Combination of (1) and M₂M₃The combinations of (a) and (b) are complementary. In summary, the switch M₁～M₄Are active switches operating at the grid frequency (e.g., 60 Hz) following a zero transition of the grid voltage sensor 52.

Referring again to fig. 5, Power Factor Correction (PFC) control logic 60 is typically configured in a first (charging) mode of operation to manage switch P in this manner₁～P₄And S₁～S₄I.e., conducting or non-conducting) to control the instantaneous current drawn from the AC source 12 so as to be in phase with the instantaneous voltage of the AC source 12. To achieve unity or near unity power factor (i.e., the case where the grid side voltage and current are in phase), the conversion device 10 includes a grid current sensor 54. In an embodiment, the current sensor 54 is configured to determine the current through the inductor 34 and provide a signal to the controller 46 indicative of the level of current drawn from the AC source 12. Thus, the signal is a grid current indication signal. In an embodiment, the controller 46 implements power factor correction by controlling the gate drive signals described above by executing the PFC logic 60. Grid current sensor 54 may include conventional components known in the art.

Zero Voltage Switching (ZVS) logic 62 is generally configured to manage switches P in such a manner₁～P₄And S₁～S₄So that they are preferably switched on and off at zero or near zero voltage. In general, to maintain a zero voltage switch for switch turn-on, current should flow in reverse from source to drain before the turn-on action, which causes the switch voltage to drop to zero. Thus, during switch turn-on, the switch only undertakes a current change, wherein the then prevailing voltage across the drain to source of the switch is always close to zero, which in turn eliminates turn-on losses to thereby achieve ZVS turn-on. For more information, U.S. application No.14/744,998 filed on 19/6/2015 (hereinafter the' 998 application, entitled "GATE drive circuit") may be filedThe' 998 application is hereby incorporated by reference as if fully set forth herein.

Fig. 7 shows the control of the switch P in a single switching frequency embodiment in a first (charging) mode of operation₁～P₄And S₁～S₄Timing diagrams of the above-described gate driving signals of the operation of (1). In the illustrated embodiment, the switch P₁～P₄And S₁～S₄Will be at the same switching frequency f_s(with a frequency-to-width ratio of 50%). To achieve a high system power density, the switching frequency f_sShould be as high as possible. P₁And P₄Gate driving signal and P₂And P₃And (4) complementation. In addition, a gate driving signal S₁And S₂Are complementary, signal S₃And S₄As well as the same. Signal trace V_pAnd V_sCorresponding to the output voltages of the primary and secondary sides of a Dual Active Bridge (DAB), and a Signal trace I_LCurrent corresponding to primary inductor, and switch P₁～P₄And S₁～S₄The timing relationship of the states of (a) is shown.

The main control logic 51 is configured to be at S₁And S₃Introduces a phase shift between the gate drive signals (i.e., see τ)₀And τ₁The time period in between). Including the switching frequency f_sAnd the determined S₁And S₃A number of factors of phase shift therebetween determine the power transferred from the primary side to the secondary side. In other words, the above factors provide two degrees of freedom to control the power transmitted. At the same time, to achieve ZVS, the phase shift must fall within a certain range, which also will switch the frequency f_sLimited to a certain value.

The main control logic 51 determines (in accordance with PFC logic 60 and ZVS logic 62) at least two parameters, which are designated g (t) and w (t) in fig. 7-8. The g (t) parameter corresponds to τ₀And τ₁Time between-while the w (t) parameter corresponds to τ₂And τ₃The time in between.

FIG. 8 is a timing chart showing waveforms of the above-mentioned g (t) and w (t) parametersThe g (t) and w (t) parameters are two parameters used by the controller 46 to determine the phase shift. The parameter fs (t) corresponding to the switching frequency f_s。

In an embodiment, main control logic 51 is executed by controller 46, wherein the functions of rectifier logic 58, PFC logic 60, and ZVS logic 62 are implemented simultaneously. In this regard, the w (t) parameter may be determined by the controller 46 according to equation (1):

equation (1)

Where vin (t) is the voltage measured on the grid side (i.e., input node 36-FIG. 5), V_outIs the measured output voltage of the converter at output node 80, andnIs the turns ratio (i.e., N) of the transformer 40_s/N_pIn which N is_sIs the number of secondary turns, and N_pIs the number of primary turns).

Equation (2)

Each phase current may be controlled by g (t), w (t), and fs (t).

As is known in the art, the parameter g (t) in equation (1) may be determined by a system designer to implement ZVS switching, for example, as seen by reference to U.S. patent No.9,729,066 (application No. 15/198,887) entitled "ELECTRIC POWER CONVERSION APPARATUS HAVING SINGLE-PHASE OPERATION mode," which is hereby incorporated by reference as if fully set forth herein. In operation, the controller 46 may cause the switching frequency f to be set during operation_sChange in real time. In other words, the controller 46 (and the lower level logic modules described herein) executing the main control logic 51 may vary P during real-time operation₁～P₄And S₁～S₄And in addition, it should be appreciated that ZVS embodiments may limit the switching frequency as also seen by U.S. patent No.9,729,066The switching frequency.

With continued reference to fig. 5, the main control logic 51 still further includes operating mode control logic 64 stored in the memory 50 and, when executed by the controller 46, configured to control the switch block 16 to assume (i) the above-described first state for the first (charging) operating mode when predetermined battery charging criteria are met, and (ii) the above-described second state for the second (motoring) operating mode when predetermined motoring criteria are met.

For example only, the predetermined battery charging criteria may include the apparatus 10 determining when the electric vehicle is in a stationary (motionless) state and ready to be charged (e.g., in a "parked" state). For example only, the predetermined motor drive criteria may include the apparatus 10 determining when the electric vehicle is in a ready-to-drive state (e.g., in a "drive" state). In this regard, the criteria for determining the driving mode may include: (i) placing the vehicle in a drive mode by inserting a key into an ignition switch, detecting the presence of the key in the vehicle cabin, or determining that the cell phone key is correct; (ii) detecting removal of the AC charging plug from the vehicle; and (iii) determining that the battery state of charge is sufficient for driving.

Fig. 10 is a simplified schematic and block diagram of an embodiment of the apparatus 10 suitable for use in a second motor drive mode of operation. When the operating mode control logic 64 determines that the device should be in the second operating mode, the controller 46 commands the switch block 16 (and in particular the relay bank 16)₂) To assume a second state in which the bi-directional AC/DC converter 18 is via the group 16₂Is electrically connected to the electric motor 14 as shown where the electrical connection is electrically closed. In the second mode of operation, the converter 18 is configured to operate functionally in embodiments as a Current Source Inverter (CSI). As described above, the charging/driving power is determined by the phase shift and the switching frequency.

In the embodiment of fig. 10, it is assumed that the electric motor 14 is a Permanent Magnet Synchronous Motor (PMSM) and the configuration as shown implements a control algorithm for operating in the second motor drive mode of operation. Fig. 10 shows a plurality of current sensors 88a, 88b and 88c for detecting respective (actual) phase currents ia, ib and ic applied to phases a, b and c of the electric motor 14, wherein the sensors generate respective phase current indicative signals, as shown. Fig. 10 also shows a plurality of comparison devices 90a, 90b and 90c and a plurality of PI (proportional integral) control blocks 92a, 92b and 92 c. Fig. 10 also shows an inverse DQ conversion block 94 and an input drive command block 96.

The illustrated embodiment implements a so-called dq model for n-phase motor control, where motor speed is determined by d-axis current (id) and motor torque is determined by q-axis current (iq). The command block 96 represents the commanded motor speed and torque as dictated by the predetermined vehicle control methodology, e.g., supplied with user input as well as various vehicle operating parameters, as is conventional in the art. Thus, id and iq are commands corresponding to desired or sought motor operating states of the motor 14. Inverse DQ transformation block 94 is configured to convert the sought motor speed and torque state into corresponding phase currents, designated as ia, ib, and ic (i.e., these are reference currents for phases a, b, and c). The actual (sensed) motor phase currents ia, ib and ic are compared with the reference phase currents and corresponding difference or error signals are generated, which are fed to corresponding PI control blocks 92a, 92b and 92 c. The PI control blocks 92a, 92B, and 92C are, in turn, configured to generate appropriate converter control parameters for each phase, where g (t) for phase a is ga, w (t) for phase a is wa, and fs (t) for phase a is fsa (e.g., ga, wa, fsa for phase a, gb, wb, fsb for phase B, and gc, wc, and fsc for phase C). These control parameters control the conversion of the DC power drawn from the battery 20 into corresponding phase currents to be applied to the electric motor.

Embodiments in accordance with the present disclosure have many advantages. One advantage is low cost. The use of one AC/DC converter to achieve both rapid charging and motoring results in a significant cost reduction of the overall power electronics system on the vehicle compared to conventional implementations that include separate AC/DC and DC/AC converters for each purpose.

Another advantage is high power density. In an embodiment, a bidirectional AC/DC converter employs GaN HEMT solid state switches in a switching module that can operate at relatively high switching frequencies > 100 kHz, which can be almost ten times as fast as the switching frequencies associated with conventional Si switches. Such high switching frequencies result in higher order harmonics that are easier to filter. This situation therefore allows the use of a much smaller output capacitor in parallel with the battery, thereby reducing the occupied space and increasing the power density.

A further advantage is high efficiency. Conventional DC/AC inverters operate in hard switching mode, which results in high switching losses, thereby tending to low switching frequencies. In an embodiment, the bi-directional AC/DC converter is configured to operate in a soft switching mode, resulting in higher efficiency. In contrast, a conventional Si switch-based inverter may have a switching frequency of 10 kHz and 96% efficiency, while a GaN HEMT switch-based inverter embodiment has a switching frequency > 100 kHz and 98% efficiency, even with an isolated transformer.

A further advantage relates to facilitating rapid charging. In conventional chargers, their power capacity is limited not only by the power of the grid, but also by the costs involved and the available space. In the case of many single-phase chargers having a power density of about 1 kW/L and three-phase chargers having a power density of about 2 kW/L, it is difficult to design any charger > 20 kW, which would require significant space (volume) in the vehicle, which is generally not available. By using the same converter for both battery charging and motor driving purposes, the charger and inverter will have the same power level capability, which makes the system particularly suitable for use in so-called fast battery charging methods, e.g. methods involving power charging stages of about 50 kW.

It will be appreciated that the electronic control unit as described herein may comprise conventional processing means known in the art capable of executing pre-programmed instructions stored in an associated memory, all in accordance with the functionality described herein. To the extent that the methods described herein are embodied in software, the resulting software can be stored in an associated memory and can also constitute an appliance for performing such methods. In view of the foregoing enabling description, implementation of certain embodiments, in software to do so, would require no more than routine application of programming techniques by one of ordinary skill in the art. Such an electronic control unit may also be of the type having a combination of both ROM, RAM, non-volatile and volatile (modifiable) memory, so that any software may be stored and still allow dynamically generated data and/or signals to be stored and processed.

Although only certain embodiments have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this disclosure. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the invention as defined in the appended claims.

Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. Accordingly, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

while one or more particular embodiments have been shown and described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present teachings.