Power converter

Abstract

The described apparatus comprises: a power conversion unit having a plurality of power stages, each power stage comprising one or more MOSFET modules, one or more gate drive units arranged to drive MOSFETs in the MOSFET modules, thereby enabling electrical power conversion by MOSFET switching; a control unit arranged to receive one or more control signals indicative of a characteristic of the required electrical power conversion and to receive the measured physical parameter from the power stage and to generate a gate drive signal for the gate drive unit to control the MOSFET, each power stage is coupled to the control unit via a single respective upstream plastic optical fiber and a single respective downstream plastic optical fiber, each power stage comprising an upstream optical fiber interface and a serializer arranged to serialize the measured physical parameters for transmission to the control unit via the upstream plastic optical fiber, for each power stage, the upstream plastic optical fiber being coupled to the control unit via a single respective upstream plastic optical fiber and a single respective downstream plastic optical fiber. The control unit comprises a downstream fiber optic interface and a serializer arranged to serialize a gate drive signal of the power stage for transmission over a downstream fiber optic via the downstream fiber optic interface. A vehicle and method are also described.

Description

Technical Field

[0001] This invention relates to power converters, and more particularly to a power converter having multiple power stages. Background Technology

[0002] Power systems consisting of one or more battery modules are commonly used to power vehicles, ships, small aircraft and other vehicles, as well as industrial applications such as mining vehicles and equipment. The flexibility of such systems also makes them attractive mobile power sources for both home and industrial use. In all these systems, it is typically necessary to convert the native DC voltage output from one or more battery modules to the different DC voltages required by the vehicle's power unit or other load units in the home and industrial systems.

[0003] Figure 1 This is a schematic diagram of vehicle 1 (e.g., a car, truck, or tractor), where power is provided by battery 2, which includes multiple battery modules. The battery power is supplied to motor 3 via an electric power chain, thereby driving the vehicle's wheels. The motor is typically an AC motor; in this case, an inverter in the power chain converts the battery's DC power into AC power to drive the AC motor. Control unit 4 can control motor 3 (e.g., based on the driver's needs) and control the power supplied by the battery.

[0004] Figure 2 This is a block diagram showing in more detail some of the interactions between power system components of a suitable electric power chain, which might be used for Figure 1 The vehicle or other application shown. Battery 11 provides DC power to power converter 12. Power converter 12 provides DC-DC conversion, changing the battery's first voltage to a second voltage for use by the inverter. In a vehicle, the first voltage is typically higher than the second voltage, and the voltage conversion is achieved by precise control switching operation of power semiconductors (e.g., MOSFETs). Inverter 13 converts the DC second voltage output from the power converter to AC voltage to supply motor 14 for driving the vehicle. Typically, the inverter and power converter can be arranged to operate bidirectionally to either use battery power for power or utilize the vehicle's motion to charge the battery.

[0005] The battery management unit (BMU) monitors the battery module and controls power delivery to the electric power chain, thereby optimizing battery life, power delivery, and charging. The power converter driver (PCD) unit 17 controls the power converter to deliver power from the battery to the motor in the desired manner (e.g., upon request from the driver or control unit). The battery management unit 16 and the power converter driver 17 can be arranged together, for example at the combined controller 15, or separately. For example, the power converter driver can be located at the power converter, while the battery management unit can be located with the battery module.

[0006] It is necessary to address the problems and limitations of existing technologies. Summary of the Invention

[0007] Power converters may have limited power handling capabilities. To improve power handling, multiple power stages can be arranged in parallel within the power converter. In such a parallel arrangement, it is important that the operation of each power stage is precisely controlled in time relative to the other power stages. For example, if the parallel power stages use pulse width modulation for switching, it is desirable that the switching is time-dependent with respect to each other power stage to avoid the switching cycle deviating slightly from the desired phase relationship. This places demands on the connectivity and communication channels for each power stage, at least in terms of the challenges of physically managing multiple cables, avoiding interference between these cables that may be close to each other, and avoiding the weight and complexity challenges associated with the electrical shielding required to prevent such interference.

[0008] This invention provides an apparatus comprising: a power conversion unit including a plurality of electrically parallel power stages, each power stage being arranged to perform bidirectional electrical power conversion between a first DC voltage and a second DC voltage. The power converter is divided into multiple power stages to improve power handling capability. The power handling capability of MOSFETs, other power converter switching components, or transistors may be limited; therefore, by dividing the power conversion into multiple parallel stages, the power handling capability can be improved.

[0009] Each power stage includes one or more MOSFET modules and one or more gate drive units, the gate drive units being arranged to deliver gate drive signals to the MOSFETs in the MOSFET modules to achieve electrical power conversion through MOSFET switching. Each power stage also includes multiple sensors arranged to measure physical parameters of the power stage. In embodiments, the MOSFETs may be other power switching components or other types of transistors, and the gate drive units may be switching control units or base control / drive units, respectively.

[0010] The device also includes a control unit spaced apart from the power conversion unit. The control unit is arranged to receive one or more control signals indicating the desired characteristics of the electrical power conversion, such as first and second DC voltages, and to receive measured physical parameters from the power stage, and to generate gate drive signals for the gate drive unit to control the MOSFETs.

[0011] Each power stage is coupled to the control unit via a single uplink plastic fiber and a single downlink plastic fiber. The uplink plastic fiber is arranged to carry measured physical parameters to the control unit for generating a gate drive signal, and the downlink plastic fiber is arranged to carry the gate drive signal from the control unit to the power stage for delivery to the MOSFET module.

[0012] Each power stage also includes an uplink fiber optic interface and a serializer arranged to serialize the measured physical parameters for transmission to the control unit via the uplink fiber optic interface over uplink plastic fiber. For each power stage, the control unit includes a downlink fiber optic interface and a serializer arranged to serialize the gate drive signals of the power stage for transmission over downlink fiber via the downlink fiber optic interface. Using only a single uplink fiber and a single downlink fiber reduces the number of connections per power stage. This is achieved by using a serializer and deserializer to convert multiple parallel signals into a single uplink and a single downlink serial data stream for each power stage. Plastic fiber is also more robust than conventional glass or silicon fiber.

[0013] Each power stage also includes a downlink fiber optic interface and a deserializer arranged to deserialize the gate drive signal received from the downlink fiber optic interface and provide the gate drive signal to the gate drive unit to control the MOSFET. The control unit may also include an uplink fiber optic interface and a deserializer arranged to deserialize measured physical parameters received from the uplink fiber optic interface for generating the gate drive signal.

[0014] Each power stage preferably includes a separate serializer IC connected to other power stages, and each power stage preferably includes a separate deserializer IC connected to other power stages. The serializer IC and deserializer IC for a given power stage can be provided as a combined serializer / deserializer IC.

[0015] The serializer can be configured to use, for example, 8b / 10b encoding or similar encoding, where multiple data bits are symbolically encoded.

[0016] The gate drive signal may include a PWM control signal.

[0017] The measured physical parameters may include one or more of the voltage, current, and temperature measured at the corresponding power level.

[0018] Each power stage preferably has a single gate drive unit configured to receive a gate drive signal and deliver the gate drive signal to two MOSFET modules, wherein the first of the two MOSFET modules is arranged on a first side of the power conversion bridge and the second of the two MOSFET modules is arranged on a second side of the power conversion bridge.

[0019] Each gate drive unit may include a first gate drive circuit and a second gate drive circuit. The first gate drive circuit may be configured to send a gate drive signal to a first MOSFET module, and the second gate drive circuit may be configured to send a gate drive signal to a second MOSFET module.

[0020] For each power stage, the serializer of the control unit can be configured to serialize the gate drive signals of one or more MOSFETs in the first MOSFET module with the gate drive signals of one or more MOSFETs in the second MOSFET module, and the downlink fiber optic interface can be configured to transmit the serialized gate drive signals through a downlink plastic fiber to the gate drive unit of the corresponding power stage.

[0021] The device may also include a digital isolator at each gate drive unit, which is arranged to isolate the gate drive signals of the first MOSFET module and the second MOSFET module.

[0022] The MOSFETs can be configured in a buck-boost configuration. Each power stage can have four MOSFETs in this configuration. Of the four MOSFETs, two can be located in a first MOSFET module and two in a second MOSFET module. The first MOSFET module can be located on the input side of the power conversion unit or the battery side, and the second MOSFET module can be located on the output side of the power conversion unit or the inverter / motor side. A reactance assembly can be placed between the two MOSFET modules.

[0023] The uplink and downlink plastic optical fibers can be configured as full-duplex optical links, enabling the control unit to communicate with the power stages via a full-duplex optical link corresponding to each power stage. Preferably, each power stage can be configured with only one full-duplex optical link.

[0024] The parallel power stages can be configured to output voltages in the range of 0 to 2000V or 5000V (e.g., 0 to 2500V), or in the range of 100 to 2000V or 5000V (e.g., 1500 to 2500V). The device can be configured to enable a combined power conversion of multiple power stage outputs in the range of hundreds of kilowatts to 10 megawatts. Alternatively, the battery voltage can be on the order of hundreds of volts, while the power stages reduce the voltage to tens of volts.

[0025] The length of the plastic optical fiber for each power level is at least 0.5 meters or 1 meter, and can be up to 5 meters or 10 meters, or even longer.

[0026] This invention provides a vehicle comprising the device described herein, a battery consisting of one or more battery modules, and an electric drive unit or motor. The device provides power conversion in either direction between the one or more battery modules and the electric drive unit. The vehicle may be a wheeled vehicle.

[0027] The present invention also provides a method for controlling a power converter comprising multiple power stages, the method comprising: receiving at a control unit one or more control signals indicating desired power conversion characteristics (e.g., first and second DC voltages) and measured physical parameters from the multiple power stages; generating gate drive signals based on the received one or more control signals and the measured physical parameters for use by a gate drive unit to control MOSFETs of one or more power stages; serializing the gate drive signals for use in the respective power stages; transmitting the serialized gate drive signals via a downlink fiber to an fiber optic interface at the respective power stage via a downlink fiber optic interface; receiving the serialized gate drive signals at the power stage and deserializing the gate drive signals at a deserializer at the respective power stage; and delivering the gate drive signals to the MOSFETs of one or more MOSFET modules to achieve power conversion by MOSFET switching.

[0028] The method may further include: measuring one or more physical parameters at the corresponding power level; serializing the measured one or more physical parameters and transmitting them to the control unit via an uplink plastic optical fiber; and deserializing the measured one or more physical parameters at the control unit.

[0029] The present invention may also provide an apparatus comprising: a power conversion unit including a plurality of power stages connected in parallel, each power stage being arranged to convert electrical power between a first DC voltage and a second DC voltage, each power stage including one or more MOSFET modules and one or more gate drive units, the one or more gate drive units being arranged to deliver gate drive signals to the MOSFETs in the MOSFET modules to achieve electrical power conversion by MOSFET switching; each power stage including a control unit spaced apart from the power conversion unit, the control unit being arranged to receive one or more control signals indicating the desired characteristics of electrical power conversion and to generate gate drive signals for the gate drive units to control the MOSFETs.

[0030] Each power stage is coupled to the control unit via a single downlink plastic fiber arranged to carry gate drive signals from the control unit to the power stage for delivery to the MOSFET module.

[0031] For each power stage, the control unit includes a downlink fiber interface and a serializer arranged to serialize the gate drive signals of that power stage for transmission over the downlink fiber via the downlink fiber interface.

[0032] The device may also include: at each power stage, a plurality of sensors for measuring physical parameters of the power stage, and a single uplink plastic optical fiber arranged to carry the measured physical parameters to a control unit for generating a gate drive signal. Each power stage may include an uplink optical fiber interface and a serializer arranged to serialize the measured physical parameters for transmission to the control unit via the uplink optical fiber interface on the uplink plastic optical fiber. Attached Figure Description

[0033] Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0034] Figure 1 A schematic diagram of a battery-powered vehicle;

[0035] Figure 2 A block diagram illustrating the interactions between power system components in the electric power chain of a pure electric vehicle is provided for greater detail.

[0036] Figure 3 A block diagram of a power converter with multiple parallel stages;

[0037] Figure 4 A detailed schematic diagram showing the connection between the controller unit and multiple power stages of the power converter;

[0038] Figure 5 This is a circuit diagram of a power converter based on a buck-boost converter.

[0039] Figure 6 A block diagram illustrating in detail the transmission method of control and measurement signals between the control unit and the gate drive unit;

[0040] Figure 7 A table showing the control and measurement signals sent and received by the serializer / deserializer at the control unit is provided. Detailed Implementation

[0041] Figure 3 This is a schematic diagram of a power converter containing multiple parallel power stages. Five power stages are shown, labeled 21-25. Other numbers of power stages can also be provided, for example, more than five or fewer, but at least two power stages are preferred. These power stages are arranged in parallel to receive the input DC voltage V. DCIN (For example, from a battery containing one or more battery modules), and provides an output DC voltage V. DCOUT(For example, supplied to an inverter to drive an AC motor). Each power stage 21-25 of the power converter is controlled by a DC-DC controller 26. Communication between the DC-DC controller 26 and the power stages 21-25 is via optical fiber 27. Each power stage uses a separate optical fiber or fiber optic cable for communication. For example, communication from the DC-DC controller 26 to power stage 21 is along optical fiber 27a, communication from the DC-DC controller 26 to power stage 22 is along optical fiber 27b, and so on. Therefore, optical fibers 27a-27e or fiber optic cables can be considered in a star or one-to-many configuration. The DC-DC controller can be located away from or at a distance from the power stages 21-25. For example, the DC-DC controller can be located near the vehicle's main controller. Figure 3 As shown, optical fibers or cables can be close to each other during the cabling from the DC-DC controller 26 to the power stage. Unlike cables, optical fibers are less susceptible to interference when they are close to each other and transmit relatively high-speed (e.g., MHz) signals along them.

[0042] Plastic optical fiber is particularly preferred because it is more robust and durable than traditional glass optical fiber. Furthermore, the signal transmission distance is relatively short, such as 1-5 meters or 1-10 meters, and since the signal frequency is in the MHz range, the higher dispersion and signal attenuation of plastic optical fiber are not a problem.

[0043] Figure 3 Fiber optic cables 27a-27e or fiber optic cables are shown connecting the DC-DC controller 26 to power stages 21-25. The fiber optic cables can be full-duplex fibers or full-duplex fiber optic cables for transmitting uplink and downlink signals. For example, downlink signals can be used to control various aspects of the power stages, such as converter switching and / or power settings, while uplink signals can be power stage-related measurement parameters, such as voltage, current, temperature, etc. Full-duplex operation is preferably achieved via full-duplex fiber optic cables, i.e., a pair of fibers, one for uplink and one for downlink. The two fibers can be integrated into a single cable. Other full-duplex configurations are also feasible, such as using two communication units on a single fiber. However, due to the scattering limitations of the plastic fiber optic material, it is preferable to use one fiber for uplink and the other for downlink.

[0044] In this embodiment, the optical transceiver may be from the Broadcom ABFR series, the MOSFET may be a SiC module from a different manufacturer, and the optical fiber may be any general-purpose plastic optical fiber compatible with the transceiver.

[0045] Figure 3Electrical connections for parallel power stages are also shown. Each power stage is connected in parallel to the input voltage line or rail via connection 28a and to the output voltage line or rail 28b. Each power stage is also connected to the ground rail or line via connection 28c.

[0046] Figure 4 This is a detailed schematic diagram of the connection between the controller unit 102 and multiple power stages, and... Figure 3 Similar, but displays more details. Figure 5 This is an example circuit diagram of the power stage section, which uses a buck-boost converter. Figure 4 This involves communication between a controller unit or control unit and a power stage, which can be used to control MOSFETs or other power converter components or switching components within the power stage.

[0047] For detailed reference Figure 4 The power converter 12' includes five power stages 21, 22, 23, 24, and 25, and... Figure 3 The power stages are similar. As mentioned earlier, the number of power stages is preferably two or more. Figure 4 Implementation examples and Figure 3 Similarly, five power levels are shown, but other numbers of power levels can also be configured. The controller unit 102 can be connected to... Figure 3 The DC-DC controller 26 is similar to, or contains, that of the DC-DC controller 26. Figure 3 DC-DC controller 26.

[0048] Figure 3 The controller unit 102 includes a processor, such as an FPGA, arranged to receive control signals C. These control signals C can be received from a vehicle main controller, which receives input from the driver, such as acceleration or deceleration. Such a vehicle main controller may include analog or predictive analysis of the required voltage to provide the necessary torque or power to the wheels. Similar configurations and considerations apply if the invention is implemented as a power converter for a domestic or industrial application, but whose power requirements originate from residential or industrial needs.

[0049] The FPGA 104 of controller 102 is programmed with a control algorithm 104a for controlling multiple power levels. This control algorithm uses signals from sensors in the power levels and control signals C to set the power converter components in the power levels to the correct operating points, thereby efficiently achieving the required power output. The FPGA outputs relatively fast switching signals to control power conversion, for example, by using pulse width modulation or setting PWM control signals. Controller unit 102 also includes communication circuit boards 121-125, units, or integrated circuits (ICs). Each power level may be equipped with a communication board. Each communication board contains a serializer S1 and a deserializer DS1, as well as two optical transceivers O1 and O4. Optical transceivers O1 and O4 are respectively connected to a duplex plastic fiber optic link consisting of fiber F1 (for downlink) and fiber F2 (for uplink). As we will describe further, each power level has multiple power converter components that need to be controlled. Therefore, multiple control signals need to be transmitted to each power level simultaneously. This invention transmits multiple control signals by using serialization and optical transceivers O1 to transmit signals along the optical fiber. These signals are then received and deserialized by an optical transceiver at the other end of the optical fiber. In one embodiment, the power stage includes a buck-boost converter comprising four MOSFETs, each requiring a control signal input at its gate. Therefore, the gate control signals need to be serialized and transmitted along the downlink fiber F1. Similarly, power stages 21-25 generate measurement signals. Multiple measurement signals are transmitted from the power stages and received via the uplink fiber by optical transceiver O4, where they are deserialized at the deserializer DS1 in the control unit.

[0050] While we have described the serializer, deserializer, and optical transceiver being placed on a communication board or IC, other arrangements are also feasible. For example, all the serializers, deserializers, and optical transceivers used for transmitting and receiving data to all power levels could be placed on a single circuit board, which could be located on the same board as the FPGA or processor. However, using a separate communication board for each power level is advantageous because it means the power system can be easily expanded if more or fewer power levels are needed. Furthermore, if the serializers, deserializers, and optical transceivers for each power level are placed on a separate circuit board, interference between signals can be reduced, such as… Figure 4 The layout shown.

[0051] Now let's describe Figure 4Power stages 21-25 are shown in the diagram. Each power stage receives a first voltage and outputs a second voltage. They are schematically represented by "A" and "B" respectively. For example, the first voltage could be 1500V DC, and the second voltage could be 2100V DC. The power stages are connected in parallel, so all power stages are connected to the same voltage. Typically, one side of a power stage can be considered the input side, used to provide power (e.g., from a battery); the other side can be considered the output side, used to output power (e.g., to an inverter for a load or AC motor). However, the power converter described herein is considered bidirectional, as indicated by the adjacent bidirectional arrows "A" and "B". Power can also be transmitted in reverse. For example, power can be regenerated from vehicle motion and returned to charge the battery.

[0052] Each power stage includes a gate drive unit 131. The gate drive unit 131 includes optical transceivers O2 and O3, for receiving signals from downlink fiber F1 and transmitting signals along uplink fiber F2, respectively. The gate drive unit also includes a deserializer DS2, a serializer S2, and one or more gate drive circuits. Figure 4 In the diagram, two gate drive circuits 135a and 135b are shown on the gate drive board 134. The gate drive board 134 also includes one or more digital isolators 136. The power stage also includes a power converter assembly. Figure 4As shown, the power converter assembly is a MOSFET, providing two MOSFET modules 141 and 142. MOSFET module 141 can be used on the low-voltage side (or battery side) of the power converter, while MOSFET module 142 can be used on the high-voltage side (or AC motor inverter side) of the power converter. The power converter can be configured as a bridge circuit and / or a buck-boost converter, as previously described. Therefore, the MOSFET modules can be configured on opposite sides of the bridge circuit or converter. The signal received along the downlink fiber F1 is received at transceiver O2, where it is converted from the optical domain to the electrical domain. The electrical signal is then sent to deserializer DS1 to deserialize the signal into a parallel signal stream. Preferably, the signal passes through digital isolator 136 before being sent to gate drive circuits 135a and 135b. The gate drive circuit sends signals to the MOSFET modules to control the gates in the modules. By equipping the high-side and low-side MOSFET modules with separate gate drive circuits, the two gate drive circuits can be isolated from each other. The isolation between the two circuits can be further improved by having the digital signal transmitted through the digital isolator. For a four-MOSFET buck-boost converter, two signals can be sent to MOSFET module 141 to control the gates of two transistors on one side of the bridge or converter (e.g., the low-voltage side). Two other signals are sent to MOSFET module 142 to control the gates of two additional transistors on the other side of the bridge or converter (e.g., the high-voltage side). While we have described dividing the four MOSFETs into two pairs, two per MOSFET module, this is only a preferred embodiment. In other embodiments, each module may provide only one MOSFET, or each module may have up to four MOSFETs, thus requiring four or only one MOSFET module. However, it is preferable to mount the MOSFETs on opposite sides of the bridge on different modules to minimize noise and interference.

[0053] The power stage 121 also includes a sensor M for measuring physical parameters at the corresponding power stage. These physical parameters may include voltage, current, and temperature. The measurement signals received from the sensor M are sent to the gate driver board 134. Figure 4 Three sensors M are shown. The gate driver board sends the measurement signal as a parallel signal to the serializer S2, which serializes it and transmits it to the optical transceiver O3 so that it can be transmitted in the optical domain to the controller unit through the uplink fiber F2.

[0054] While we have described two gate drive circuits 135a and 135b that communicate with the controller unit via a full-duplex fiber optic link and control the two MOSFET modules in each power stage, the power stage can also have its gate drive circuits arranged on separate gate drive boards. A first gate drive circuit can be located on the first gate drive board of the first MOSFET module 141 on one side of the control bridge or converter, and a second gate drive circuit can be located on the second gate drive board of the second MOSFET module 142 on the other side of the control bridge or converter. Accordingly, the first gate drive circuit on the first gate drive board also receives measurements from sensors on one side of the bridge or converter, while the second gate drive circuit on the second gate drive board receives measurements from sensors on the other side of the bridge. In this arrangement and the full-duplex fiber optic link discussed, an intermediate communication unit is needed to separate the transmitted / received, arriving / receiving communications from the fiber optic link to the corresponding first and second gate drive circuits. This can include a digital isolator. This dual-board layout is less than ideal because signal transmission is more complex. Furthermore, any measurement signals unrelated to the two MOSFET modules must be transmitted by one of the gate drive boards.

[0055] Figure 4 Five power levels are shown, each controlled by a controller unit with a full-duplex fiber optic link. These five (or other numbers of) power levels are substantially identical to each other.

[0056] Now let's describe Figure 5 The circuit diagram illustrates gate drive circuits 135a and 135b, MOSFET modules 141 and 142, and the circuitry for the buck-boost converter. As mentioned above, the buck-boost converter can be a four-MOSFET type buck-boost converter. Besides MOSFETs, other power converter components or switching units, such as other types of transistors, can be used. However, for the applications described herein, MOSFETs are preferred, especially silicon carbide (SiC) MOSFETs, because they switch faster than silicon (Si) MOSFETs, resulting in higher power delivery efficiency. Figure 5 In the diagram, these four MOSFETs are designated 152, 153, 154, and 155, respectively. Another key component of the buck-boost converter is the reactance component. Figure 5 The inductor is shown in the middle. Two gate drive circuits, 135a and 135b, are also shown in the figure.

[0057] Gate drive circuit 135a sends a signal to first MOSFET module 141, which includes MOSFET module circuit board 141a and a pair of MOSFETs 152 and 153, both denoted by reference numeral 141b. Gate drive circuit 135b sends a signal to second MOSFET module 142, which includes MOSFET module circuit board 142a and a pair of MOSFETs 154 and 155, both denoted by reference numeral 142b. The MOSFETs in each pair are connected in series. One end of inductor 160 is connected to a first node n1 between the two MOSFETs 152 and 153 of the first MOSFET module. The other end of the inductor is connected to a second node n2 between the two MOSFETs 154 and 155 of the second MOSFET module.

[0058] The buck-boost converter is configured to convert the first voltage V1 ( Figure 5 The left side shows the voltage on the power rail / line in the upper left corner, which is converted into the second voltage V2. Figure 5 The right side shows the voltage on the power rail / line in the upper right corner. The source terminal of MOSFET 152 is connected to the V1 voltage, and its drain terminal is connected to node n1, which in turn is connected to the source of MOSFET 153. The drain of MOSFET 153 is connected to the ground rail / line 180. As previously mentioned, the gates of MOSFETs 152 and 153 are controlled by a signal from the gate drive circuit 135a, provided via the MOSFET module board 141a. On the left side of the circuit diagram is capacitor C3, which is connected between the V1 voltage rail and the ground rail 180. Capacitor C3 is an output smoothing capacitor used to smooth voltage ripple on the V1 rail, especially when power returns to the V1 rail. Additionally, capacitor C1 is connected between the source terminal of MOSFET 152 and the drain terminal of MOSFET 153. Capacitor C1 is a buffer capacitor used to suppress voltage spikes and oscillations that may occur when the MOSFETs are turned on and off. Figure 5 On the V1 side of the circuit, there are also sensors 171 and 172. Sensor 171 is a voltage monitor used to monitor the voltage on the voltage rail V1. Sensor 172 is a temperature monitor, located on the MOSFET module board 141, used to monitor the temperature and prevent the MOSFET, which can carry high current, from overheating.

[0059] Sensor 173 may be positioned near inductor 160, which is connected between nodes n1 and n2. Sensor 173 may be a temperature sensor, such as a thermistor, for monitoring the temperature of the inductor.

[0060] Figure 5The right side is a partial mirror image of the left side. As previously described, MOSFET module 142 includes MOSFETs 154 and 155. The source terminal of MOSFET 154 is connected to the V2 voltage, and its drain terminal is connected to node n2, which in turn is connected to the source of MOSFET 155. The drain terminal of MOSFET 155 is connected to ground rail / line 180. As previously described, the gates of MOSFETs 154 and 155 are controlled by a signal from gate drive circuitry 135b, provided via MOSFET module board 142a. On the far right of the circuit diagram is capacitor C4, which is connected between the V2 voltage rail and ground rail 180. Capacitor C4 is an output smoothing capacitor used to smooth voltage ripple on the V2 voltage rail when power is supplied. Additionally, capacitor C2 is connected between the source terminal of MOSFET 154 and the drain terminal of MOSFET 155. Capacitor C2 is also a buffer capacitor used to suppress voltage spikes and oscillations that may occur when the MOSFETs are turned on and off. Similar to the V1 side of the circuit, the V2 side of the circuit has sensors 175 and 176. Sensor 175 is a voltage monitor used to monitor the voltage on the voltage rail V2. Sensor 176 is a temperature monitor, located on the MOSFET module board 142, used to monitor the temperature of the MOSFET.

[0061] A current monitor 174 is positioned between nodes n1 and n2 (e.g., near and in series with the inductor) to monitor the current flowing through inductor 160. The measurement signal from the current monitor is sent to the gate drive circuit. In fact, the measurement signals from all sensors 171-176 are sent to the gate drive board 134.

[0062] Figure 5 An optical fiber link 27 connected to the gate drive circuit is also shown for receiving signals from the controller unit 102 and sending measurement signals to the controller unit.

[0063] Now let's describe the working principle of the buck-boost converter. MOSFETs conduct in pairs. When MOSFETs 152 and 155 are on, voltage V1 is applied across inductor 160, and energy is stored in the inductor. After conduction, current flows and increases, flowing through MOSFET 152, inductor 160, and MOSFET 155. During this period, MOSFETs 153 and 154 are off. The switching of the MOSFET pairs is complementary, so when MOSFETs 152 and 155 are off, MOSFETs 153 and 154 are on. When this happens, the energy stored in the inductor causes current to flow through MOSFETs 153 and 154. After MOSFETs 153 and 154 are on (and MOSFETs 152 and 155 are off), the current will slowly decrease. Through this operation and other switching operations, the buck-boost converter operates similarly to a switching power supply, which can be used to increase or decrease voltage. Specifically, its operating principle is similar to a buck-boost bidirectional converter, which can operate in voltage, current, or power control modes.

[0064] Figure 5 The converter device shown can be used to output a voltage on rail V2 that is higher or lower than the input voltage rail V1 (i.e., boost or buck), and power can flow bidirectionally. Example voltages for V1 and V2 can be 1500V and 2100V, or 1500V and 700V. Multiple power stages can be configured to handle power from hundreds of kilowatts to 10 megawatts, such as a peak power of 600kW or 3MW.

[0065] In one embodiment, the MOSFET is a SiC MOSFET module, and the MOSFET module board is designed by the applicant.

[0066] As previously described, the present invention uses serialization and fiber optic links to transmit control signals between the controller unit 102 and the gate drive unit 131 of the power stage. Figure 6 The signal transmission method and the corresponding measurement signal return method are shown in more detail.

[0067] Figure 6 A system-on-a-chip 225 is provided, which includes a microprocessor 210 and an FPGA core 220, connected via an AXI interface 215. The microprocessor is programmed with a control algorithm that uses voltage and current measurement signals to determine operating settings. The microprocessor can also receive control signals (e.g., from the vehicle's main processor, controlled by a driver) Figure 4 As shown in C). The FPGA core receives the operating settings determined by the microprocessor and generates / processes these signals to produce digital signals for controlling the power stage. Figure 4In this configuration, the microprocessor and FPGA core are combined into FPGA 102. The FPGA core generates LVCMOS digital signals 230 and sends them to the serializer / deserializer IC 235. The serializer / deserializer IC 235 is shown as a single IC, but the serializer and deserializer can be separate chips or units, such as Analog Devices' MAX 9205 serializer and MAX 9206 deserializer. This serializer / deserializer pair can operate at a clock speed of around 10 MHz, for example, between 16 MHz and 40 MHz. The serializer receives a parallel signal stream and converts it into a serial signal stream. Serialization can be in SerDes form and can be done using 8b / 10b SerDes encoding. This encoding uses an 8-bit stream and encodes it into 10-bit symbols. The advantage of 8b / 10b encoding is its ability to achieve DC balance, bounded differences, and sufficient state changes for clock recovery. Other similar encoding methods can achieve the same functionality, for example, encoding multiple bits into bit symbols. After the signal is serialized, it will be sent to the optical transceiver 245 in the form of a low-voltage differential digital signal (LVDS) 240. Figure 6 The serializer / deserializer 235 in the middle corresponds to Figure 4 The serializer S1 and deserializer DS1 are located in the optical transceiver 245. Figure 4 The optical transceivers O1 and O4 are located in the chip. The system-on-chip 225, serializer / deserializer 235, and optical transceiver 245 can all be mounted on a control PCB 201, which is spaced apart from or away from the gate driver unit or PCB 202. The optical transceiver 245 transmits control signals along an optical fiber link 250 (e.g., a duplex plastic fiber), which are received by the optical transceiver 255 on the gate driver unit 202, corresponding to... Figure 4 The gate drive unit 131 is located in the optical transceiver 255. The optical transceiver 255 outputs an LVDS signal 260 to a serializer / deserializer 265, also located on the gate drive unit 202. The serializer / deserializer 265 outputs a transistor control signal 270a to control the gate of the power stage transistor. For example, the transistor control signal may include two sets of control signals, one for each of the two MOSFET modules 280. The return of sensor measurement data is roughly the reverse of the transmission of control data. The serializer / deserializer 265 receives measurement data, which may include any of the following signals: voltage measurement signals, current measurement signals, and temperature measurement signals from sensors (e.g., sensors 171-176). The serializer / deserializer 265 may also receive fault signals, such as signals generated by the MOSFET modules. Measurement data and fault signals are as follows: Figure 6As shown at 270b in the diagram. Transmission of measurement data includes serialization and providing it as an LVDS signal to optical transceiver 255. The optical signal is transmitted from the transceiver along optical fiber 250 to optical transceiver 245. The optical transceiver sends the measurement signal as an LVDS signal to serializer / deserializer 235 and provides the measurement data as an LVCMOS digital signal to the on-chip system. Serializer / deserializer 265 and optical transceiver 255 are located on the gate drive unit, while MOSFET module 280 can be located on a different board or circuit. MOSFET module 280 corresponds to... Figure 4 MOSFET modules 141 and 142 in the middle.

[0068] Feedback from the sensors to the FPGA control unit is used to control the switching of MOSFETs, thereby controlling PWM and power delivery. The measurement signal and control can be considered as a closed-loop feedback, and PI loop feedback can be used.

[0069] Figure 7 It provides more information about Figure 6 This table contains information about the input or output signals and voltages of the serializer / deserializer 235. The upper part of the table represents the serializer's inputs, which are combinations of control signals sent to the gate drive circuit and control signals for the serializer itself. The last three items in the upper part of the table are labeled CTRL0, CTRL1, and CTRL2, providing the SYNC signal, the enable / disable signal for serial data output, and the clock signal, all of which are used for the operation of the serializer. As mentioned above, the clock signal can be a clock signal with an operating frequency of 10-40MHz, for example, 16MHz or 19.2MHz. Now look at the first ten items listed in the table, which are the data or control signals D0-D9 sent by the serializer to the gate drive circuit. Data D0-D9 contains data used to control the two MOSFET modules 141 and 142 and to operate the sensor M on the gate drive board. Data D0 is the clock signal sent to the gate drive circuit to drive the analog-to-digital converter (ADC) on the gate drive board. The ADC measures the voltage, current, and temperature on the gate drive board. Data D1 and D4 are logic signals used to initiate the ADC conversion of the measurement sensor. Data D2 and D6 are signals used for the top and bottom MOSFETs in the conduction bridge. D3 and D7 are inverting signals used to improve the DC balance of the signal on the optical link and to check for errors in D2 and D6. D5 is a data signal used to reset the fault logic of the gate driver when a fault is reported. D8 is the enable signal for the overcurrent detection system, and D9 is an odd parity bit calculated by the transmission controller. This bit is copied and checked on the gate driver circuitry or board to detect single-bit errors.

[0070] The lower half of the table represents the data received by the deserializer from the gate drive circuit or gate drive board. It can be seen that the various data points, such as D0-D9, are all measurement data, such as the voltage, temperature, and current measurements discussed earlier. For example, D0 is a high-voltage measurement (e.g., Figure 5 The output voltage V2 in the output voltage is the ADC conversion result. D1 is the current measurement value (e.g., the output voltage V2 in the output voltage). Figure 5 The table shows the ADC conversion results of the current sensor 174 (measured value). D2 is the ADC conversion result of the temperature measurement. D3 is an inverting signal used to improve the DC balance of the signal on the optical link and check for errors in D2. D4 is unused. D5 is a fault logic signal, where multiple fault logic signals are multiplexed into D5. D6 is another ADC conversion of the temperature measurement. D7 is an inverting signal used to improve the DC balance of the signal on the optical link and check for errors in D5. D8 is the loop return of the TxData signal D1, used in the FPGA to calibrate the timing of the received ADC measurement conversion results. D9 is the odd parity bit, calculated by the gate driver based on the transmitted data. This bit is copied and checked on the FPGA to detect single-bit errors. Additionally, the end of the table contains some control signals related to the deserializer itself, such as control signals related to the clock recovered from the deserializer.

[0071] While we have described above a buck-boost converter with four MOSFETs providing bidirectional power conversion, a unidirectional converter containing only two MOSFETs can also be provided. This converter is similar to... Figure 5 The converter shown does not include MOSFETs 154 and 155. The inductor output is directly connected to the output voltage line V2 via the smoothing capacitor C4. This type of converter can be called a buck converter. The unidirectional nature of the two MOSFET converters means that power conversion will be provided to the second voltage rail V2. Using a buck converter also reduces the voltage at V2 compared to V1.

[0072] Although specific embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art will understand that various variations and modifications can be made to these embodiments without departing from the scope of the invention as defined by the claims.

Claims

1. An apparatus comprising: The power conversion unit includes multiple power stages connected in parallel, each power stage being arranged to perform bidirectional power conversion between a first DC voltage and a second DC voltage. Each power stage includes one or more MOSFET modules, one or more gate drive units arranged to deliver gate drive signals to the MOSFETs in the one or more MOSFET modules to achieve electrical power conversion through MOSFET switching, and multiple sensors arranged to measure physical parameters of the power stage. A control unit, spaced apart from the power conversion unit, is arranged to receive one or more control signals indicating desired power conversion characteristics, and to receive measured physical parameters from the power stage, and to generate gate drive signals for the gate drive unit to control the MOSFET. Each power stage is coupled to the control unit via a single corresponding uplink plastic fiber and a single corresponding downlink plastic fiber. The uplink plastic fiber is arranged to carry measured physical parameters to the control unit for generating the gate drive signal, and the downlink plastic fiber is arranged to carry the gate drive signal from the control unit to the power stage for delivery to the MOSFET module. Each power stage includes an uplink fiber optic interface and a serializer arranged to serialize measured physical parameters for transmission to the control unit via the uplink fiber optic interface over the uplink plastic optical fiber. The control unit for each power stage includes a downlink fiber interface and a serializer, the serializer being arranged to serialize the gate drive signals of the power stage for transmission over the downlink fiber via the downlink fiber interface.

2. The apparatus according to claim 1, wherein, Each power stage also includes a downlink fiber optic interface and a deserializer, the deserializer being arranged to deserialize gate drive signals received from the downlink fiber optic interface and provide the gate drive signals to the gate drive unit to control the MOSFET. The control unit further includes an uplink fiber optic interface and a deserializer, the deserializer being arranged to deserialize the measured physical parameters received from the uplink fiber optic interface for generating the gate drive signal.

3. The apparatus according to claim 1 or 2, wherein, Each power stage includes a separate serializer IC that connects to other power stages.

4. The apparatus according to any one of the preceding claims, wherein, Each power stage includes a separate deserializer IC that is connected to other power stages.

5. The apparatus according to any one of the preceding claims, wherein, The serializer is configured to use 8b / 10b encoding.

6. The apparatus according to any one of the preceding claims, wherein, The gate drive signal includes a PWM control signal.

7. The apparatus according to any one of the preceding claims, wherein, The measured physical parameters include one or more of the voltage, current, and temperature measured at the corresponding power level.

8. The apparatus according to any one of the preceding claims, wherein, Each power stage has a single gate drive unit configured to receive the gate drive signal and deliver the gate drive signal to two MOSFET modules, the first of which is arranged on a first side of the power conversion bridge and the second of which is arranged on a second side of the power conversion bridge.

9. The apparatus according to claim 8, wherein, The gate driving unit includes a first gate driving circuit and a second gate driving circuit. The first gate driving circuit is arranged to send a gate driving signal to the first MOSFET module, and the second gate driving circuit is arranged to send a gate driving signal to the second MOSFET module.

10. The apparatus according to claim 8 or 9, wherein, For each power level, the serializer of the control unit is configured to serialize the gate drive signals of one or more MOSFETs in the first MOSFET module with the gate drive signals of one or more MOSFETs in the second MOSFET module, and the downlink fiber optic interface is configured to transmit the serialized gate drive signals through the downlink plastic fiber to the gate drive unit of the corresponding power level.

11. The apparatus of any one of claims 8 to 10, further comprising a digital isolator at each gate drive unit, the digital isolator being arranged to provide isolation between gate drive signals of the first MOSFET module and the second MOSFET module.

12. The apparatus according to any one of the preceding claims, wherein, The MOSFET is configured as a buck-boost converter.

13. The apparatus according to any one of the preceding claims, wherein, The first MOSFET module includes two MOSFETs, and the second MOSFET module includes two MOSFETs.

14. The apparatus according to any one of the preceding claims, wherein, The uplink and downlink plastic optical fibers are configured as full-duplex optical links, enabling the control unit to communicate with the power level through a full-duplex optical link corresponding to each power level.

15. The apparatus according to any one of the preceding claims, wherein, The electrically parallel power stage is configured to output a voltage in the range of 0 to 2000V or 0 to 5000V, such as 0 to 2500V, or in the range of 100 to 2000V or 100 to 5000V, such as 1500 to 2500V.

16. The apparatus according to any one of the preceding claims, wherein, The combined conversion power output from the multiple power stages ranges from tens of kW to 10 MW.

17. The apparatus according to any one of the preceding claims, wherein, The plastic optical fiber connected to each power level can be up to 5 meters or 10 meters long.

18. The apparatus according to any one of the preceding claims, wherein, The data rates of the serializer and deserializer are between 10 MHz and 40 MHz.

19. A vehicle comprising a device according to any one of the preceding claims, one or more battery modules, and an electric drive unit, the device providing power conversion in any direction between the one or more battery modules and the electric drive unit.

20. A method for controlling a power converter comprising multiple power stages, the method comprising: The control unit receives one or more control signals indicating the desired power conversion characteristics, as well as measured physical parameters from the plurality of power levels. Based on one or more received control signals and measured physical parameters, a corresponding gate drive signal is generated for the gate drive unit to control the MOSFETs of the one or more power stages; The gate drive signal is serialized for use in the corresponding power stage; The serialized gate drive signal is transmitted on the downlink fiber to the fiber interface at the corresponding power stage via the downlink fiber interface. The serialized gate drive signal is received at the power stage, and the gate drive signal is deserialized at the deserializer of the corresponding power stage. as well as The gate drive signal is delivered to the MOSFETs of one or more MOSFET modules to achieve power conversion through MOSFET switching.

21. The method of claim 20, further comprising: Measure one or more physical parameters at the corresponding power level; One or more measured physical parameters are serialized and transmitted to the control unit via an uplink plastic optical fiber; as well as The measured one or more physical parameters are deserialized at the control unit.

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