Vehicle traction inverter temperature control system

Abstract

The present disclosure provides a "Vehicle Traction Inverter Temperature Control System". A vehicle system includes a pump configured to circulate coolant for a traction inverter and a controller. The controller can be configured to operate the pump at a predetermined speed in response to a temperature of the traction inverter falling outside of a first range or a requested flow rate of the pump falling outside of a second range, and otherwise operate the pump at a speed based on a difference between the temperature and a temperature associated with the coolant.

Description

Technical Field

[0001] This application generally relates to temperature control systems for traction power electronics devices used in electrified vehicles. Background Technology

[0002] Electrified vehicles, such as hybrid electric vehicles (HEVs), rely on power electronics to control their electrified powertrains. During operation, the heat generated by these power electronics is typically proportional to the power losses they incur. Summary of the Invention

[0003] A vehicle system includes a pump and a controller, the pump being configured to circulate coolant for a traction inverter. The controller may be configured to: operate the pump at a predetermined speed in response to the temperature of the traction inverter falling outside a first range or the pump's requested flow rate falling outside a second range; otherwise, operate the pump at a speed based on the difference between the temperature and the temperature associated with the coolant.

[0004] One method includes, via a controller, operating a pump to circulate coolant at a predetermined rate in response to a first threshold temperature of the traction inverter; operating the pump at the predetermined rate in response to a second threshold flow rate of the pump; otherwise, operating the pump at a rate based on the difference between the temperature and the junction temperature of the traction inverter.

[0005] A vehicle system includes a pump and a controller, the pump being configured for use in the coolant circulation of a traction inverter. The controller may be configured to operate the pump at one of two predetermined speeds in response to the temperature of the traction inverter falling within a first range and the requested flow rate of the pump falling outside a second range; to operate the pump at a speed based on the difference between the temperature and the junction temperature of the traction inverter in response to the temperature falling within the first range and the requested flow rate falling within the second range; and to operate the pump at one of the two predetermined speeds in response to the temperature falling outside the first range. Attached Figure Description

[0006] Figure 1 This is a flowchart of the temperature control system for the vehicle's power electronics.

[0007] Figure 2 This is a schematic diagram of a hybrid vehicle, showing a typical powertrain and energy storage components.

[0008] Figure 3 This is a schematic diagram of the cooling system for the power electronics in an electrified vehicle.

[0009] Figure 4This is a flowchart of the temperature control system for the traction power electronics system of an electrified vehicle.

[0010] Figure 5 This is a graph showing the relationship between coolant temperature and coolant flow rate in a traction power electronics system.

[0011] Figure 6 This is a flowchart for estimating the coolant temperature of the traction power electronics system in an electrified vehicle.

[0012] Figure 7A and Figure 7B This is a flowchart of the temperature control system for the traction power electronics system of an electrified vehicle.

[0013] Figure 8 This is a block diagram of the coolant flow rate control system for an electric pump. Detailed Implementation

[0014] This document describes embodiments of the present disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the invention in different ways. As will be understood by those skilled in the art, various features shown and described with reference to any of the drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments of typical applications. However, for a particular application or implementation, various combinations and modifications of these features may be necessary based on the teachings of this disclosure.

[0015] In hybrid electric vehicles (HEVs) / electric vehicles (EVs), the power electronics of the drivetrain include an inverter system controller (ISC) and a DC / DC converter. The ISC includes a DC / AC inverter for the motor (e.g., a motor inverter or generator inverter) and a variable voltage converter (VVC). The ISC is a critical component for transferring power between the traction battery and the motor (motor / generator). The DC / DC converter is a critical component for generating low voltage from the traction battery for low-voltage loads. Power losses occurring during ISC operation include losses from power switches (such as IGBTs / diodes in motor / generator inverters) and losses from power inductors and the IGBTs / diodes in the VVC. Most of these power losses are converted into heat in the power switches / diodes, causing the junction temperatures of the power switches / diodes and the inductor temperatures to increase if not cooled. If the temperature of the power switches exceeds limits or thresholds (e.g., 115°C, 125°C, or 150°C), it can cause physical damage to the power switches or modules. To remove some of the heat generated by power electronic devices, ISCs typically include a cooling system that circulates a cooling fluid (e.g., a coolant such as water, ethylene glycol, diethylene glycol, or propylene glycol) to dissipate heat and regulate the temperature of the IGBT / diode and inductor within their operating range. Typically, coolants have high heat capacity, low viscosity, and are non-toxic, chemically inert, corrosion-resistant, and electrically insulating. The coolant can be circulated through the cooling loop by a pump (e.g., an electric pump). Typically, the operation of the electric pump in the cooling system is simply to turn it on or off, and the pump speed is usually operated at a relatively constant rate when on. However, at high coolant flow rates, the thermal resistance (i.e., the resistance to heat transfer from the power device / module to the coolant) decreases, thus increasing heat dissipation, while at low coolant flow rates, the thermal resistance increases, thus reducing heat dissipation. Thermal resistance is a function of the heat sink area and the contact area between the coolant and the power device. Therefore, a controller can be used to change the pump speed to regulate the coolant flow rate, thereby regulating heat dissipation. Implementing a variable-speed pump increases cost and complexity; however, this disadvantage is offset by the advantage of reducing power consumption by operating the pump at lower speeds when higher speeds are not required. For example, a pump operating at high speed produces a high coolant flow rate, but the pump consumes more power. Conversely, the low coolant flow rate resulting from a low pump speed consumes less pump power. As an example, consider a model pump where doubling the pump speed doubles the flow rate and quadruples the pressure. However, to double the speed, the required power increases eightfold.

[0016] Conventional ISC cooling systems typically operate in two control modes: In the first mode, the coolant flow rate is turned on at a constant (maximum) value once the system is powered on. This ensures cooling of the power electronics (e.g., IGBTs / diodes and inductors) under worst-case conditions (e.g., maximum power loss and maximum coolant temperature). In the second mode, the coolant flow rate is turned off (e.g., zero) when the system enters idle mode. As a result, conventional coolant flow rate control has drawbacks, and HEVs / EVs typically operate under many load conditions. For example, high power flow through the ISC can lead to high power loss and thus generate more heat, potentially requiring a high coolant flow rate to cool the power electronics (e.g., IGBTs / diodes and inductors). Conversely, low power flow through the ISC can result in low power loss and generate very little heat, so a low coolant flow rate is sufficient to cool the power electronics (e.g., IGBTs / diodes and inductors). During low-power flow conditions, using a high coolant flow rate requires the pump to consume more energy than is needed, since a low flow rate is sufficient. By reducing the flow rate, the system can reduce wasted energy, thereby increasing the effective driving range of HEV / EV.

[0017] Furthermore, maintaining a minimum constant coolant flow rate can lead to higher temperature swings and temperature cycling due to insufficient cooling of power module components during operation, potentially shortening the power module's lifespan. Temperature variations typically cause mechanical stress, and temperature cycling can amplify the effects of this stress. Significant variations in the junction temperature of power devices (e.g., IGBTs / diodes) can result in high mechanical forces on the integrated circuits, chips, or components of the power devices (e.g., IGBTs / diodes), which can shorten their operational lifespan. While conventional cooling systems operating at maximum coolant flow rates can maintain low junction temperatures under both high and low power output conditions, additional pump power is used during low power output periods, which can be reduced.

[0018] Figure 1 This is a flowchart of a temperature control system for vehicle power electronics. Here, the coolant flow rate control system is configured to optimize the cooling of the ISC by automatically adjusting the cooling system operation using the HEV / EV operating status, thereby optimizing coolant pump power consumption by utilizing IGBT / diode junction temperature / changes.

[0019] Figure 1The coolant flow rate control system comprises several steps. First, in Box 4, the ISC thermal safe operating area (SOA), or operating area, is calculated. Based on the relationship between the ISC coolant temperature and the coolant flow rate, the safe operating area (SOA) can be defined as the operating area in which the ISC ensures maximum power / current output under any circumstances, such as maximum torque / power delivery required by the drive. The SOA boundary defines the minimum coolant flow rate for any given coolant temperature, and while controlling the coolant pump flow rate, this minimum flow rate must be met to satisfy vehicle dynamics, such as sudden full throttle opening (WOT), without overheating the power unit.

[0020] ISC SOA is defined as promoting power unit operation under worst-case conditions where the power module generates the highest power loss and heat. This typically occurs when the ISC is providing maximum load power. Even under worst-case conditions, based on the control system, the junction temperature (Tj) should be below the threshold temperature (e.g., 125°C or 150°C).

[0021] Furthermore, coolant flow rate and coolant temperature can significantly affect junction temperature. Thermal resistance (Rth) is a function of coolant flow rate, power module chip size, and material properties; therefore, variations in flow rate will affect the power module's heat dissipation. For each coolant flow rate, the maximum permissible coolant temperature can be expressed by the following equation:

[0022] T 冷却剂 =150-ΔT=150-P 损耗 *R th (1) Where P 损耗 This refers to the power loss of the ISC inverter when it outputs the maximum current at the highest DC bus voltage. This can also be called the coolant operating limit.

[0023] Next, in step 6, the controller can limit the maximum IGBT / diode junction temperature reference T. * jmax The maximum temperature change ΔT of the junction temperature * jmax ΔTj is defined as the average junction temperature rise of the power module (PM) over a period of time (e.g., 5s, 10s, or 20s). This control objective ΔT* jmax It adaptively changes based on various driving modes (such as city driving, highway driving, hill climbing, or cruise). ΔT * jmaxIt can also be configured to avoid continuous high-temperature cycling of the power module (PM) (e.g., variations of 50°C or higher), which may increase PM losses and potentially shorten PM lifespan. A power module (PM) includes power devices such as insulated-gate bipolar junction transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), diodes, solenoids, inductors, capacitors, resistors, conductors, or contactors.

[0024] Peak junction temperature rise of power module (PM) T * jmax This is a control objective set to provide a rapid response (e.g., 0.5, 1, 5, or 10 milliseconds) to dynamic or transient high-power output demands, such as a vehicle suddenly accelerating after being stopped for a period of time at a traffic light. Transient high-power output demands include power output changes exceeding a threshold. * jmax It can be set to adapt to various environmental conditions, such as hot or cold regions, high or low altitudes, humid or dry places, or operate year-round. * jmax It can have two values, T * jmax-1 and T * jmax-2 , so that (T) * jmax-1 <T * jmax-2 It is designed to control the thermal operation of ISC within the safety protection band.

[0025] In step 8, the controller senses the junction temperature (T) of the IGBT / diode of the motor inverter. j_M_INV ), IGBT / diode junction temperature of generator inverter (T) j_G_INV IGBT / diode junction temperature (T) of variable voltage converter (VVC) j_vvc In step 10, the controller estimates the power loss of the module, and in step 12, the controller estimates the coolant temperature. These inputs of the ISC coolant flow rate control strategy 2 generate a target coolant flow rate in step 14, which is then used in step 16 to control the speed of the coolant pump motor.

[0026] Figure 2 A vehicle is depicted, and specifically, an electrified vehicle 112 that can be referred to as a plug-in hybrid electric vehicle (PHEV). Although in Figure 2The diagram illustrates a PHEV, but these concepts also apply to conventional vehicles, as the components of a conventional vehicle are a subset of those shown in EV 112. Here, the plug-in hybrid electric vehicle 112 may include one or more motors 114 mechanically coupled to a hybrid transmission 116. The motors 114 may be capable of operating as either motors or generators. Furthermore, the hybrid transmission 116 is mechanically coupled to an engine 118. The hybrid transmission 116 is also mechanically coupled to a drive shaft 120, which is mechanically coupled to wheels 122. The motors 114 can provide propulsion and deceleration capabilities when the engine 118 is started or stopped. The motors 114 can also act as generators and can provide fuel economy benefits by recovering energy that would normally be lost as heat in friction braking systems. The motors 114 can also reduce vehicle emissions by operating the engine 118 at more efficient speeds under certain conditions and by allowing the hybrid electric vehicle 112 to operate in electric mode with the engine 118 off. The electrified vehicle 112 may also be a battery electric vehicle (BEV). In a BEV configuration, the engine 118 may be absent. In other configurations, the electrified vehicle 112 may be a full hybrid electric vehicle (FHEV) without plug-in capability.

[0027] The traction battery or battery pack 124 stores energy that can be used by the motor 114. The vehicle battery pack 124 can provide a high-voltage direct current (DC) output. The traction battery 124 can be electrically connected to one or more power electronics modules 126. One or more contactors 142 can isolate the traction battery 124 from other components when open and connect the traction battery 124 to other components when closed. The power electronics module 126 is also electrically connected to the motor 114 and is capable of bidirectionally transferring energy between the traction battery 124 and the motor 114. For example, the traction battery 124 can provide DC voltage, while the motor 114 can operate with three-phase alternating current (AC). The power electronics module 126 can convert the DC voltage to three-phase AC current to operate the motor 114. In regenerative mode, the power electronics module 126 can convert the three-phase AC current from the motor 114, which acts as a generator, to a DC voltage compatible with the traction battery 124.

[0028] Vehicle 112 may include a variable voltage converter (VVC) 152 electrically connected between traction battery 124 and power electronics module 126. VVC 152 may be a DC / DC boost converter configured to increase or increase the voltage supplied by traction battery 124. By increasing the DC bus voltage, current demand can be reduced, resulting in a reduction in the wiring size of power electronics module 126 and motor 114. Furthermore, motor 114 can operate with better efficiency and lower losses.

[0029] In addition to providing energy for propulsion, the traction battery 124 can also provide energy for other vehicle electrical systems. Vehicle 112 may include a DC / DC converter module 128 that converts the high-voltage DC output of the traction battery 124 into a low-voltage DC supply compatible with low-voltage vehicle loads. The output of the DC / DC converter module 128 may be electrically connected to an auxiliary battery 130 (e.g., a 12V battery) for charging the auxiliary battery 130. Low-voltage systems may be electrically connected to the auxiliary battery 130. One or more electrical loads 146 may be connected to a high-voltage bus. The electrical loads 146 may have an associated controller that operates and controls the electrical loads 146 as appropriate. Examples of electrical loads 146 may be fans, electric heating elements, and / or air conditioning compressors.

[0030] The electrified vehicle 112 can be configured to charge the traction battery 124 from an external power source 136. The external power source 136 can be a connection to an electrical outlet. The external power source 136 can be electrically connected to a charger or an electric vehicle power supply unit (EVSE) 138. The external power source 136 can be a power distribution network or grid provided by a power company. The EVSE 138 can provide circuitry and controls to regulate and manage energy transfer between the power source 136 and the vehicle 112. The external power source 136 can supply DC or AC power to the EVSE 138. The EVSE 138 can have a charging connector 140 for insertion into a charging port 134 of the vehicle 112. The charging port 134 can be any type of port configured to transfer power from the EVSE 138 to the vehicle 112. The charging port 134 can be electrically connected to a charger or an on-board power conversion module 132. The power conversion module 132 can regulate the power supplied from the EVSE 138 to provide appropriate voltage and current levels to the traction battery 124. The power conversion module 132 can be connected to the EVSE 138 to coordinate the power delivery to the vehicle 112. The EVSE connector 140 may have pins that mate with corresponding notches of the charging port 134. Alternatively, various components described as electrically connected or linked can use wireless inductive connections to deliver power.

[0031] One or more wheel brakes 144 may be provided for decelerating and preventing the vehicle 112 from moving. Wheel brakes 144 may be hydraulically actuated, electrically actuated, or a combination thereof. Wheel brakes 144 may be part of a braking system 150. Braking system 150 may include other components for operating wheel brakes 144. For simplicity, the figure depicts a single connection between braking system 150 and one of wheel brakes 144. Connections between braking system 150 and other wheel brakes 144 are implicit. Braking system 150 may include a controller for monitoring and coordinating braking system 150. Braking system 150 may monitor braking components and control wheel brakes 144 to achieve vehicle deceleration. Braking system 150 may respond to driver commands and may also operate automatically to achieve features such as stability control. The controller of braking system 150 may implement a method that applies a requested braking force when requested by another controller or subfunction.

[0032] The electronic modules in vehicle 112 can communicate via one or more vehicle networks. The vehicle network can include multiple channels for communication. One channel of the vehicle network can be a serial bus, such as a Controller Area Network (CAN). One of the channels of the vehicle network can include Ethernet as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802 series standards. Other channels of the vehicle network can include discrete connections between modules and can include power signals from auxiliary battery 130. Different signals can be transmitted through different channels of the vehicle network. For example, video signals can be transmitted via high-speed channels (e.g., Ethernet), while control signals can be transmitted via CAN or discrete signals. The vehicle network can include any hardware and software components that facilitate the transmission of signals and data between modules. Figure 2 The vehicle network is not shown, but it can be implied that the vehicle network can be connected to any electronic module present in vehicle 112. A vehicle system controller (VSC) 148 may be present to coordinate the operation of various components.

[0033] Typically, VVC 152 is configured as a boost converter. VVC 152 may include an input terminal that can be connected to the terminals of traction battery 124 via contactor 142. VVC 152 may include an output terminal connected to the terminals of power electronics module 126. VVC 152 can be operated such that the voltage at the output terminal is greater than the voltage at the input terminal. Vehicle 112 may include a VVC controller that monitors and controls electrical parameters (e.g., voltage and current) at various locations within VVC 152. In some configurations, the VVC controller may be included as part of VVC 152. The VVC controller can determine an output voltage reference. VVC controllers can be based on electrical parameters and voltage references. The control signal is determined to be sufficient to enable the VVC 152 to achieve the desired output voltage. In some configurations, the control signal can be implemented as a pulse width modulation (PWM) signal, where the duty cycle of the PWM signal is varied. The control signal can operate at a predetermined switching frequency. The VVC controller can use the control signal to command the VVC 152 to provide the desired output voltage. The specific control signal for the operation of the VVC 152 can be directly related to the boost voltage provided by the VVC 152.

[0034] refer to Figure 2 VVC 152 can boost or “raise” the voltage potential of the electrical power supplied by traction battery 124. Traction battery 124 can provide high voltage (HV) DC power. In some configurations, traction battery 124 can provide a voltage between 150 volts and 400 volts. Contactor 142 can be electrically connected in series between traction battery 124 and VVC 152. When contactor 142 is closed, HV DC power can be transferred from traction battery 124 to VVC 152. Input capacitor can be electrically connected in parallel with traction battery 124. Input capacitor can reduce any voltage and current ripple. VVC 152 can receive HV DC power and boost or “raise” the voltage potential of the input voltage according to the duty cycle. Typically, output capacitor is electrically connected between the output terminal of VVC 152 and the input terminal of power electronics module 126 to stabilize the bus voltage and reduce voltage and current ripple at the output terminal of VVC 152.

[0035] Figure 3 This is a schematic diagram of a cooling system 300 for power electronic devices in an electrified vehicle. The cooling system 300 includes an ISC 302, a DC / DC converter 304, a coolant pump 306 (e.g., an electric pump), and a radiator 308. Here, coolant flows through a series of pipes and devices to remove heat from the DC / DC converter and the ISC. In this illustration, a single ISC and DC / DC converter are present; however, in other embodiments, multiple ISCs or DC / DC converters may be present. Furthermore, in this illustration, the ISC and DC / DC converter are connected in series; however, the cooling system may be configured such that the ISC and DC / DC converter are connected in parallel. In another embodiment, multiple elements within the ISC are utilized, which may be connected in series, in parallel, or a combination of series and parallel, wherein these elements include heat sinks for power electronic devices, semiconductor devices, mechanical devices, or conductors. The advantage of having parallel elements is that gate valves can be added to control the flow of coolant, allowing coolant to flow to some devices while inhibiting coolant flow to others, thereby maximizing the cooling effect of the coolant.

[0036] Figure 4 This is a flowchart 400 of the temperature control system for the traction power electronics system of electrified vehicles. Figure 4 The coolant flow rate control system comprises several steps. First, in block 404, the controller calculates the ISC thermal safe operating area (SOA), or operating area. Based on the relationship between the ISC coolant temperature and the coolant flow rate, the safe operating area (SOA) can be defined as the operating area in which the ISC operates to ensure maximum power / current output under any circumstances, such as drive demand for maximum torque / power delivery. The SOA boundary defines the minimum coolant flow rate for a given coolant temperature, and while controlling the coolant pump flow rate, the minimum flow rate must be met to accommodate changes in vehicle dynamics (e.g., sudden full throttle opening (WOT)) without overheating the power unit.

[0037] ISC SOA is defined as promoting power unit operation under worst-case conditions where the power module generates the highest power loss and heat. This typically occurs when the ISC is providing maximum load power. Based on the control system, the junction temperature (Tj) should be lower than the threshold temperature even under worst-case conditions (e.g., 125°C or 150°C).

[0038] As disclosed above, coolant flow rate and coolant temperature can significantly affect junction temperature. Since thermal resistance (Rth) is a function of coolant flow rate, power module chip size, and material properties, variations in flow rate will affect the heat dissipation of the power module. For each coolant flow rate, the maximum permissible coolant temperature can be represented by Equation 1 disclosed above.

[0039] Next, in step 406, the controller limits the maximum IGBT / diode junction temperature reference T. * jmax and the maximum change in junction temperature ΔT * jmax ΔTj (the average power module (PM) junction temperature rise over a period of time) can be within a time interval of 5, 10, 15, or 20 seconds. This control target ΔT... * jmax It is configured to adaptively change based on various driving modes (such as city driving, highway driving, hill climbing or cruising), or environmental conditions (such as high or low temperature, humid or dry conditions, or high or low altitude)). ΔT * jmax It can also be configured to avoid continuous high-temperature cycling of the power module (PM) (e.g., variations of 50°C or higher), which may increase PM losses and potentially shorten PM lifespan.

[0040] Peak junction temperature T of power module (PM) * jmaxThis is a control objective set to provide a rapid response (e.g., 0.5, 1, 5, or 10 milliseconds) to dynamic or transient high-power output demands, such as a vehicle suddenly accelerating after being stopped for a period of time at a traffic light. Transient high-power output demands include power output changes exceeding a threshold. * jmax It can be set to adapt to various environmental conditions, such as hot or cold regions, high or low altitudes, humid or dry places, or operate year-round. * jmax There may be two values ​​T * jmax-1 and T * jmax-2 , so that (T) * jmax-1 <T * jmax-2 It is designed to control ISC heat within the safety protection band.

[0041] In step 408, the controller senses the junction temperature (T) of the IGBT / diode of the motor inverter. j_M_INV ), IGBT / diode junction temperature of generator inverter (T) j_G_INV IGBT / diode junction temperature (T) of variable voltage converter (VVC) j_vvc Temperature sensing can be performed using a thermocouple coupled to the power device or a structure integrated into the power device and configured to measure temperature (e.g., a diode or other structure integrated into the power device such as an IGBT).

[0042] In step 410, the controller estimates the power loss of the module, and in step 412, the controller estimates the coolant temperature. These inputs of the ISC coolant flow rate control strategy 2 generate a target coolant flow rate in step 414, which is then used to control the speed of the coolant pump motor in step 416.

[0043] Figure 5 This is a diagram 500 illustrating the relationship between coolant temperature 502 and coolant flow rate 504 in a traction power electronics system. For a given coolant temperature 502, there exists a relationship that can be established based on equations (such as T...). 冷却剂 =150-ΔT=150-P 损耗 *R th , where P 损耗 This refers to the power loss when the ISC inverter outputs maximum current at the highest DC bus voltage, and R changes as the current rate changes. th The coolant flow rate is calculated based on the change, therefore the coolant temperature profile based on the flow rate has multiple operating points 506, such that operation in the safe operating area (SOA) 508 will keep the power unit below the temperature threshold. Figure 4 When this relationship is used in the control strategy, the coolant flow rate 504 output is the setpoint, and the controller operates the pump at the setpoint.

[0044] Figure 6 This is a flowchart 600 for estimating the coolant temperature of a traction power electronics system for an electrified vehicle. In step 602, the controller receives a non-boost state of the power converter (e.g., VVC) (e.g., operating in non-boost mode) and proceeds to step 604, where the controller branches based on the duration of the non-boost state exceeding a threshold. If the non-boost state exceeds the threshold, the controller branches to step 606 and outputs a coolant temperature equal to the junction temperature of the power unit of the VVC. Otherwise, the controller branches to step 608, and the controller monitors the output current of the power inverter used for the motor configured as a motor, and proceeds to step 610. In step 610, the controller branches based on the output current being less than a threshold current for a period of time. Here, the threshold (e.g., such as an inverter current threshold) is shown as 30A; however, this threshold can vary based on the design and drive capability of the electric powertrain. If the current is less than the threshold for a period of time greater than the time threshold, the controller branches to step 612 and sets the coolant temperature to the junction temperature of the power unit of the motor inverter. Otherwise, the controller branches to step 614. In step 614, the controller monitors the power inverter output current of the motor configured as a generator and proceeds to step 616. In step 616, the controller branches based on the output current being less than a threshold current for a certain period of time. If the current is less than the threshold for a period of time greater than the threshold, the controller branches to step 618 and sets the coolant temperature to the junction temperature of the power device of the generator inverter. Otherwise, the controller branches to step 620. In step 620, the controller monitors the junction temperature and power losses of the power module and proceeds to step 622. In step 622, the controller calculates the coolant temperature based on the junction temperature and power losses. If the current is greater than the threshold or the time is less than the specified period, the system has not yet reached equilibrium, and therefore the power losses of the power electronic devices should be taken into account in the calculation.

[0045] Figure 7A and Figure 7B This is flowchart 700 of the temperature control system for the traction power electronics system of an electrified vehicle. Here, if the measured junction temperature is lower than T... * jmax-1 Then the target coolant flow rate is set to the minimum boundary, if T j >T * jmax-2If the target coolant flow rate is less than the minimum boundary of the SOA, then the target coolant flow rate is set to the maximum boundary. Otherwise, the target coolant flow rate is obtained by using a proportional-integral-derivative (PID) based coolant flow rate control method, which includes feedforward control to provide a fast dynamic response, while PID feedback reduces steady-state tracking error. Their sum is compared to the SOA limit such that i) if the sum is less than the minimum boundary of the SOA, the final output coolant flow rate is set to the minimum coolant flow rate; ii) if the sum is greater than the maximum boundary of the SOA, the final output coolant flow rate is set to the maximum coolant flow rate; and iii) otherwise, the sum is set to the final output coolant flow rate.

[0046] In step 702, the controller will receive T * jmax-1 T * jmax-2 and ΔT * jmax In step 704, the controller will receive T j And in step 706, if T j >T jmax-1 If T j ≤T jmax-1 Then the controller will branch to step 708. In step 708, the controller will set the pump speed to the minimum coolant flow rate. In step 710, if T... j <T jmax-2 Then the controller will branch to step 714. If T j ≥T jmax-2 Then the controller will branch to step 712. In step 712, the controller will set the pump speed to the maximum coolant flow rate.

[0047] In step 714, the controller estimates the coolant temperature and proceeds to step 716. Figure 6 A flowchart for coolant temperature estimation is shown; however, this disclosure is not limited to... Figure 6 The illustration.

[0048] After the coolant temperature is estimated, the data flows along two parallel paths: a feedforward path and a feedback path. The feedback path includes steps 716 through 720, while the feedforward path is described in step 722.

[0049] In step 716, the controller will calculate ΔT j For example, ΔT j It can be represented as T j -T 冷却剂 The controller will proceed to step 718 to calculate the error “e”, for example, e can be represented as ΔT*. jmax -ΔT jThe controller then proceeds to step 720 to provide proportional-integral-derivative (PID) regulation. In parallel with these steps, the controller also performs a feedforward coolant flow rate estimate in step 722.

[0050] It is possible Figure 8 The example shown demonstrates the implementation of feedforward estimation using ΔT. * jmax Coolant temperature T 冷却剂 The feedforward coolant flow rate is calculated using the ISC SOA curve. As an example, the feedforward coolant flow rate can be calculated from... Figure 5 The current coolant temperature (T) is obtained from this. 冷却剂 ) and the maximum change in junction temperature of IGBT / diode (ΔT) * jmax This is used to output the coolant flow rate. For example, consider the current coolant temperature (T). 冷却剂 The maximum change in IGBT / diode junction temperature is 70℃ (ΔT). * jmax The operating point is 5℃. Figure 5 The graph shows a coolant flow rate of 8 L / min. Maximum variation in IGBT / diode junction temperature (ΔT) * jmax The maximum operating point is 506 and the current coolant temperature is (T). 冷却剂 The difference between ) . However, if the current coolant temperature (T 冷却剂 The maximum change in IGBT / diode junction temperature (ΔT) is 70℃. * jmax If the temperature is 9℃, the coolant flow rate will increase to 11L / min.

[0051] The outputs from the feedback and feedforward control steps are used to calculate the total coolant flow rate in step 724. The output of the total coolant flow rate step 724 is input to step 726, where the controller branches to step 712 based on the output exceeding the maximum boundary. If the output does not exceed the maximum boundary, the controller proceeds to step 728. In step 728, the output of the total coolant flow rate from step 724 is input to step 728, where the controller branches to step 708 based on the output being less than the minimum boundary. If the output exceeds the minimum boundary, the controller proceeds to step 730. In step 730, the controller outputs the target coolant flow rate (i.e., sets the speed of the electric pump) and proceeds to step 732. In step 732, the controller returns and continues evaluating the operation; otherwise, the system stops.

[0052] In step 732, the controller branches based on the state of the ISC operation. For example, when the ISC system is running (e.g., in operating mode), the temperature controller returns to step 704. When the ISC system is not running (e.g., stopped), the controller branches to stop.

[0053] Figure 8 This is a block diagram of a coolant flow rate control system for an electric pump. The control system 800, executed by the controller, includes a proportional-integral-derivative (PID) regulator 802 that provides input to an ISC thermal safe operating area (SOA) determination block 804. The PID regulator 802 receives an error term (e.g., the output of step 718) based on the maximum temperature change term caused by the temperature difference offset (e.g., the output of step 716). Together with the output of the PID block 802, the SOA determination block 804 includes feedback from a flow rate calculator 806 that calculates the flow rate based on the coolant temperature. The SOA block 804 may include, for example,... Figure 5 The analysis is shown below. The controlled object model 808 uses the output of SOA block 804 to output the junction temperature and coolant temperature, which are then calculated in block 810 to calculate the difference, which is fed back to the PID controller. The controlled object model 808 can be used to drive an electric coolant pump at a flow rate determined by SOA constraints.

[0054] Key differences / advantages of the disclosed system include: cooling optimization and automatic (e.g., dynamic) operation of the cooling system in response to HEV / EV driving (such as city driving, highway driving, hill climbing, or cruising) to achieve maximum cooling performance. Adaptive features are used to dynamically control the coolant flow rate to automatically meet demand-based responses to real-world conditions. Closed-loop control ensures high-performance operation, while open-loop control requires no feedback adjustments. Focus is placed on monitoring and controlling maximum junction temperature and junction temperature variations to achieve high performance. Real-time estimated coolant temperature is used for dynamic control of the coolant flow rate. Adaptive coolant flow rate automatically matches drive demand, drive mode, and drive conditions, thereby improving energy savings. Increased PM durability and extended inverter / vehicle life are achieved by reducing power module junction temperature rise, oscillation, and cycling.

[0055] The control logic or functions executed by the controller can be represented by flowcharts or similar diagrams in one or more accompanying figures. These diagrams provide representative control strategies and / or logic that can be implemented using one or more processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Therefore, the various steps or functions shown can be executed in the order shown, in parallel, or in some cases omitted. Although not always explicitly shown, those skilled in the art will recognize that one or more of the shown steps or functions can be repeatedly executed depending on the specific processing strategy used. Similarly, the processing order is not necessarily necessary to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic can be implemented primarily in software executed by a microprocessor-based vehicle, engine, and / or powertrain controller (such as a controller). Of course, depending on the specific application, the control logic can be implemented in software, hardware, or a combination of software and hardware using one or more controllers. When implemented in software, the control logic can be provided in one or more computer-readable storage devices or media storing data that provides code or instructions for computer execution to control the vehicle or its subsystems. Computer-readable storage devices or media may include one or more of a number of known physical devices that utilize electrical, magnetic, and / or optical memory to store executable instructions and associated calibration information, operating variables, etc.

[0056] The processes, methods, or algorithms disclosed herein can be transmitted to, or implemented by, a processing device, controller, or computer, which may include any existing programmable electronic control unit or a dedicated electronic control unit. Similarly, the processes, methods, or algorithms can be stored in various forms as data and instructions executable by a controller or computer, including but not limited to information permanently stored on non-writable storage media (such as read-only memory (ROM) devices) and information reproducibly stored on writable storage media (such as floppy disks, magnetic tapes, optical discs (CDs), random access memory (RAM) devices, and other magnetic and optical media). The processes, methods, or algorithms can also be implemented as software executable objects. Alternatively, the processes, methods, or algorithms can be implemented wholly or partially using suitable hardware components (such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices) or a combination of hardware, software, and firmware components.

[0057] While exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms covered by the claims. The terminology used in this specification is descriptive and not restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure. As previously described, features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or superiority over other embodiments or prior art implementations with respect to one or more desired characteristics, those skilled in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system properties depending on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described with respect to one or more characteristics as less desirable than other embodiments or prior art implementations are not outside the scope of this disclosure and may be desired for a particular application.

[0058] According to the present invention, a vehicle system is provided, the vehicle system comprising: a pump configured for use in coolant circulation of a traction inverter; and a controller configured to operate the pump at a predetermined speed in response to the temperature of the traction inverter falling outside a first range or the requested flow rate of the pump falling outside a second range, otherwise operating the pump at a speed based on the difference between the temperature and the temperature associated with the coolant.

[0059] According to one embodiment, the temperature associated with the coolant is defined by the junction temperature of the variable voltage converter of the traction inverter.

[0060] According to one embodiment, the temperature associated with the coolant is defined by the junction temperature of the motor inverter of the traction inverter.

[0061] According to one embodiment, the temperature associated with the coolant is defined by the junction temperature of the generator inverter of the traction inverter.

[0062] According to one embodiment, the speed is limited by the predetermined speed.

[0063] According to the present invention, a method includes, via a controller, operating a pump to circulate coolant at a predetermined rate in response to a temperature of a traction inverter exceeding a first threshold; operating the pump at the predetermined rate in response to a requested flow rate of the pump exceeding a second threshold; otherwise, operating the pump at a rate based on the difference between the temperature and the junction temperature of the traction inverter.

[0064] According to one embodiment, the junction temperature is associated with the variable voltage converter of the traction inverter.

[0065] According to one embodiment, the junction temperature is associated with the motor inverter of the traction inverter.

[0066] According to one embodiment, the junction temperature is associated with the generator inverter of the traction inverter.

[0067] According to one embodiment, the invention is further characterized in that the junction temperature is limited according to the magnitude and duration of the output current of the traction inverter.

[0068] According to one embodiment, the invention is further characterized in that the junction temperature is limited according to the operating mode of the variable voltage converter of the traction inverter.

[0069] According to the present invention, a vehicle system is provided having a pump and a controller, the pump being configured for use in the coolant circulation of a traction inverter, the controller being configured to: operate the pump at one of two predetermined speeds in response to the temperature of the traction inverter falling within a first range and the requested flow rate of the pump falling outside a second range; operate the pump at a speed based on the difference between the temperature and the junction temperature of the traction inverter in response to the temperature falling within the first range and the requested flow rate falling within the second range; and operate the pump at one of the two predetermined speeds in response to the temperature falling outside the first range.

[0070] According to one embodiment, the junction temperature is associated with the variable voltage converter of the traction inverter.

[0071] According to one embodiment, the junction temperature is associated with the motor inverter of the traction inverter.

[0072] According to one embodiment, the junction temperature is associated with the generator inverter of the traction inverter.

[0073] According to one embodiment, the junction temperature is defined based on the magnitude and duration of the output current of the traction inverter.

[0074] According to one embodiment, the junction temperature is limited based on the operating mode of the variable voltage converter of the traction inverter.

[0075] According to one embodiment, the speed is limited by the two predetermined speeds.

Claims

1. A vehicle system comprising: A pump configured for use in the coolant circulation of a traction inverter; and The controller is configured to: In response to the traction inverter's temperature falling outside a first range or the pump's requested flow rate falling outside a second range, the pump operates at a predetermined speed, wherein the first range is defined by two junction temperature reference values ​​of the power modules in the traction inverter, and the second range is defined by the thermally safe operating area of ​​the traction inverter. Otherwise, the pump is operated at a rate based on the difference between the stated temperature and the temperature associated with the coolant.

2. The system as claimed in claim 1, wherein, The temperature associated with the coolant is defined by the junction temperature of the variable voltage converter of the traction inverter.

3. The system as described in claim 1, wherein, The temperature associated with the coolant is defined by the junction temperature of the motor inverter of the traction inverter.

4. The system as claimed in claim 1, wherein, The temperature associated with the coolant is defined by the junction temperature of the generator inverter of the traction inverter.

5. The system as claimed in claim 1, wherein, The speed is limited by the predetermined speed.

6. A method for temperature control of a vehicle traction inverter, comprising: Through the controller In response to the traction inverter temperature falling outside a first range or the pump's requested flow rate falling outside a second range, the pump operates at a predetermined speed, wherein the pump is configured for use in the coolant circulation of the traction inverter, the first range being defined by two junction temperature reference values ​​of the power modules in the traction inverter, and the second range being defined by the thermally safe operating area of ​​the traction inverter. Otherwise, the pump is operated at a rate based on the difference between the stated temperature and the junction temperature of the traction inverter.

7. The method of claim 6, wherein, The junction temperature is associated with the variable voltage converter of the traction inverter.

8. The method of claim 6, wherein, The junction temperature is associated with the motor inverter of the traction inverter.

9. The method of claim 6, wherein, The junction temperature is associated with the generator inverter of the traction inverter.

10. The method of claim 6, further comprising defining the junction temperature based on the magnitude and duration of the output current of the traction inverter.

11. The method of claim 6, further comprising defining the junction temperature according to the operating mode of the variable voltage converter of the traction inverter.

12. A vehicle system comprising: A pump configured for use in the coolant circulation of a traction inverter; and The controller is configured to: In response to the traction inverter's temperature falling within a first range and the pump's requested flow rate falling outside a second range, the pump is operated at one of two predetermined speeds, wherein the first range is defined by two junction temperature reference values ​​of the power modules in the traction inverter, and the second range is defined by the thermally safe operating area of ​​the traction inverter. In response to the temperature falling within the first range and the requested flow rate falling within the second range, the pump is operated at a rate based on the difference between the temperature and the junction temperature of the traction inverter. In response to the temperature falling outside the first range, the pump is operated at one of the two predetermined speeds.

13. The system of claim 12, wherein, The junction temperature is associated with the variable voltage converter of the traction inverter.

14. The system of claim 12, wherein, The junction temperature is associated with the motor inverter of the traction inverter.

15. The system of claim 12, wherein, The junction temperature is associated with the generator inverter of the traction inverter.

16. The system of claim 12, wherein, The controller is further configured to limit the junction temperature based on the magnitude and duration of the output current of the traction inverter.

17. The system of claim 12, wherein, The controller is further configured to limit the junction temperature according to the operating mode of the variable voltage converter of the traction inverter.

18. The system of claim 12, wherein, The speed is limited by the two predetermined speeds.

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