CN117681732A

CN117681732A - Battery heating method, system, vehicle and medium

Info

Publication number: CN117681732A
Application number: CN202311866868.5A
Authority: CN
Inventors: 马国龙; 曹金满; 朱明�; 赵成
Original assignee: Shanghai Jidu Automobile Co Ltd
Current assignee: Shanghai Jidu Automobile Co Ltd
Priority date: 2023-12-29
Filing date: 2023-12-29
Publication date: 2024-03-12

Abstract

The embodiment of the application provides a battery heating method, a battery heating system, a vehicle and a medium. The battery heating system comprises: the second end of the power battery is respectively connected with the second end of the first connecting switch and the second end of the inverter, the first end of the first connecting switch is connected with the second end of the bus capacitor and the first end of the second connecting switch, and the second end of the second connecting switch is connected with the motor. When the temperature is lower than a first temperature threshold value and the riding state is an unoccupied state, the first connection switch and the second connection switch are controlled to be disconnected; controlling the inverter to generate a first heating current for heating the power battery; when the temperature is lower than a first temperature threshold value and the riding state is the passenger state, the first connecting switch is controlled to be opened, and the second connecting switch is controlled to be closed; the inverter is controlled to generate a second heating current for heating the power battery. And the power battery is heated by utilizing different heating circuits according to the riding state of the passenger, so that the heating efficiency and the electric energy utilization rate are improved while the passenger demand is met.

Description

Battery heating method, system, vehicle and medium

Technical Field

The present disclosure relates to the field of vehicle control technologies, and in particular, to a battery heating method, a system, a vehicle, and a medium.

Background

In a new energy vehicle, a battery is used as a power source of an electric vehicle, and the vehicle is driven to run by supplying power to a motor. However, the prior art batteries exhibit significant performance degradation at low temperatures. Therefore, in order to enable the battery to function normally, the battery is heated. For example, the battery is heated by a liquid heater or an electric heater. However, this heating system has various problems such as low heating efficiency, low heating speed, and high power consumption.

Disclosure of Invention

The embodiment of the application provides a battery heating method, a battery heating system, a vehicle and a medium, which are used for improving the scheme of battery heating efficiency.

In a first aspect, an embodiment of the present application provides a battery heating method, where the battery heating method is applied to a battery heating system, and the battery heating system is: the controller is respectively in communication connection with the power battery, the first connecting switch, the inverter and the motor; the first end of the power battery is respectively connected with the first end of the bus capacitor and the first end of the inverter, the second end of the power battery is respectively connected with the second end of the first connecting switch and the second end of the inverter, the first end of the first connecting switch is connected with the second end of the bus capacitor and the first end of the second connecting switch, and the second end of the second connecting switch is connected with the motor;

The method comprises the following steps:

acquiring a temperature representative of the power battery and a seating state of an occupant in a vehicle cabin;

when the temperature is lower than a first temperature threshold value and the riding state is an unoccupied state, the first connection switch and the second connection switch are controlled to be disconnected; controlling the inverter to generate a first heating current for heating the power battery;

when the temperature is lower than a first temperature threshold value and the riding state is a passenger state, the first connecting switch is controlled to be opened, and the second connecting switch is controlled to be closed; the inverter is controlled to generate a second heating current for heating the power battery.

In practical application, a proper power battery heating mode is selected by comprehensively considering the temperature of a battery and the riding state of passengers in a vehicle cabin. Specifically, when heating is required (i.e., when the battery temperature is lower than the first temperature threshold), and no occupant sits in the vehicle cabin, the power battery can be warmed up with the first heating current that does not need to flow through the bus capacitor, and the heating efficiency and the electric power utilization can be effectively improved. If a passenger sits in the vehicle cabin, the power battery is heated by the second heating current in order to avoid noise generated during the heating process and to influence the riding experience of the passenger. In the heating process, the heating requirement and the riding experience requirement of the passengers can be simultaneously met.

Optionally, the controlling the inverter to generate a second heating current for heating the power battery includes:

controlling a first switching device group in the inverter to be opened and controlling at least one switching device in a second switching device group to be closed so that the second heating current flows through the bus capacitor, the motor and the power battery in a heating period; wherein the second heating current is a direct current.

In practical applications, the second switching device, the bus capacitor, the motor and the power battery together form a second heating circuit, in which the second heating circuit is arranged. In the circuit, an LC resonance circuit is formed by a bus capacitor and an equivalent inductance in a three-phase winding in the motor. In the process of charging and discharging the bus capacitor and the equivalent inductor, the heating of the power battery is realized. Because the direct current is adopted as heating current, when the direct current flows through the motor, vortex cannot be generated on the motor, so that vortex loss cannot occur, and the problem of overheating of the motor cannot occur.

Optionally, the controlling the opening of the first switching device group in the inverter and the closing of at least one switching device in the second switching device group includes: and if the first switching device group in the inverter is controlled to be opened, and the three switching devices in the second switching device group are controlled to be closed, the power battery is connected with the three switching devices, the three windings in the motor and the bus capacitor, so that the second heating current is generated by three-phase direct current flowing through the three switching devices and the three windings.

The inverter is an inverter for converting direct current into three-phase alternating current, and switching devices in the inverter can be divided into two groups of 3 switching devices each. Three paths of direct currents of the 3 switching devices respectively flow through three-phase windings of the motor, namely, three-phase direct currents simultaneously flow through the windings of the motor, no phase difference exists between currents in the three-phase windings, that is, alternating magnetic fields cannot be generated in a rotor of the motor, no torque pulsation is generated, and therefore NVH of a vehicle is enabled to perform better.

Optionally, the method further comprises: and controlling the second switching device group to be opened and controlling at least one switching device in the first switching device group to be closed, and generating a discharging circuit comprising the inverter, the motor and the bus capacitor so as to release electric energy in the bus capacitor in a discharging period.

In practical application, since the electric charge is repeatedly oscillated in the second heating circuit in the heating period, the electric charge is gradually consumed in the oscillation process, so that the second heating current is gradually reduced, and the heating capacity is gradually reduced. At this time, it is necessary to discharge the charge on the capacitor, that is, to establish a discharge circuit, to open each switching device in the second switching device group, and to close the corresponding switching device in the first switching device, thereby generating a discharge circuit including the bus capacitor, the motor, and the inverter.

Optionally, the heating period is greater than the discharge period.

In practical application, in order to improve the heating efficiency of the power battery, the inverter is controlled to operate according to the heating period and the discharging period when the power battery is heated by the second heating circuit and the second heating current. Since the amount of charge in the capacitor is not much during discharging, the discharging task can be completed in a short time. Therefore, during the heating process, it is necessary to ensure that the heating period is greater than the discharging period, that is, the duty cycle of the second switching device group is greater than the duty cycle of the first switching device when the duty cycle of each switching device in the inverter is controlled.

Optionally, the controlling the inverter to generate a first heating current for heating the power battery includes:

controlling the inverter to generate a first heating current, wherein the first heating current does not flow through the bus capacitor after the first connecting switch is disconnected, so that the power battery is heated by the first heating current; wherein the first heating current is a low frequency current less than a specified frequency threshold.

In the motor drive control circuit, when the battery temperature is low, it is necessary to heat the battery. The controller controls the first connection switch to be turned off, thereby generating a heating power supply circuit not including the bus capacitor, and since the heating current does not need to flow through the bus capacitor, the heating power is not consumed by the bus capacitor. The heating power supply circuit generates heating current which accords with preset current parameters, the appointed current frequency in the preset current parameters is low frequency (for example, 10 Hz to 50 Hz), and under the low-temperature condition, the internal resistance of the battery has the characteristic of large alternating current impedance of the low-frequency current, so that the heating rate of the battery by using the low-frequency current is higher than that of the high-frequency, that is, the heating efficiency of the first heating current is higher by using the characteristic of large low-frequency internal resistance of the battery. In addition, because the current flowing through the motor is low-frequency current, the consumption electric energy of the motor is lower than that of the high-frequency current, and the electric energy utilization rate is improved.

Optionally, if a heating termination condition is met, controlling the inverter to terminate generating the first heating current, and controlling the first connection switch to be closed; wherein the heating termination condition includes at least:

the detected temperature of the power cell is greater than a second temperature threshold.

In practical applications, when the power battery is heated by the first heating current, the first heating current has a lower current frequency. When the first heating current flows through the motor, the eddy current effect is obviously lower than that generated by the first target current, in other words, when the first heating current is utilized to heat the power battery, the motor cannot obviously raise the temperature under the effect of the eddy current effect, and the temperature of the motor caused by the low-frequency first heating current is ignored. Therefore, in the heating process, only the heating temperature of the power battery needs to be monitored in real time, and when the temperature of the power battery reaches the second temperature threshold value, the first heating current is stopped, and the heating of the power battery is stopped. Other adverse effects brought in the heating process can be avoided while the heating requirement is met.

Optionally, the controlling the first connection switch to be opened includes: and the first connecting switch is controlled to be disconnected, the first end of the power battery is connected with the first end of the inverter, and the second end of the power battery is connected with the second end of the inverter, so that the first heating current flows through a heating circuit comprising the power battery, the inverter and the motor.

In the motor drive control circuit, when the battery temperature is low, it is necessary to heat the battery. The controller controls the first connecting switch to be disconnected, so that a heating circuit without the bus capacitor is generated, and the first heating current does not need to flow through the bus capacitor, so that electric energy cannot be consumed by the bus capacitor, and the heating efficiency of the power battery can be effectively improved. The first heating current is a low-frequency (for example, 10 hz to 50 hz) current, and under the condition of low temperature, the internal resistance of the battery has the characteristic of large alternating current impedance to the low-frequency current, so that under the condition of the same current, the heating rate of the battery by using the low-frequency current is higher than that of the battery by using the high-frequency current, that is, the heating efficiency by using the low-frequency current is higher. In addition, because the current flowing through the motor is low-frequency current, the consumption electric energy of the motor is lower than that of the high-frequency current, and the electric energy utilization rate is improved.

Through controlling the operating condition of the first connecting switch in the motor driving circuit, the heating circuit and the driving circuit can be rapidly switched, the driving requirement is ensured, and meanwhile, the efficient heating of the power battery can be realized.

Optionally, the terminating heating condition further comprises at least one of: the detected temperature of the motor is greater than a third temperature threshold; and/or, the heating duration of the first heating current reaches a duration threshold; and/or receiving a vehicle driving instruction; and/or detecting an occupant in the vehicle cabin; and/or receiving a heating termination instruction sent by a user.

In practical applications, there are a number of conditions for terminating the heating, and in addition to detecting the temperature threshold as described above, the heating time may be set (for example, the heating time may be set to 20 minutes after the user starts the vehicle for 20 minutes). In addition, the vehicle can be selected according to the working state of the vehicle, for example, when a user starts the vehicle in a cabin, or remotely starts the vehicle, or when the user sends a heating termination instruction, the heating of the power battery is terminated, the first connecting switch is controlled to be closed, the bus capacitor is connected into the driving circuit, and the controller controls the inverter to provide driving current. Still alternatively, the first heating current may need to flow through the motor, creating eddy currents in the motor, causing the motor to warm up. Therefore, in order to avoid damage to the motor, the temperature of the motor needs to be monitored during the heating of the battery. When the controller finds that the temperature of the motor is greater than the third temperature threshold, it considers that the motor safety temperature range is exceeded, and the heating needs to be stopped. In the scheme, the controller controls the inverter to work to generate heating current and driving current with various frequencies and magnitudes. The motor is prevented from being damaged due to overhigh temperature while the heating requirement of the battery is met. Through the mode, the heating requirement of the power battery is met, and meanwhile, the heating can be stopped timely and the driving state can be switched to according to the requirement, so that the rapid switching of the heating circuit and the driving circuit is realized.

In practical application, after heating is terminated, the controller controls the first connection switch to be closed, so as to generate a driving circuit comprising a bus capacitor. Furthermore, the driving circuit is used for supplying power to the motor, so that the driving effect is realized. By means of the first connection switch, a fast switching of the heating circuit and the drive circuit can be achieved.

Optionally, after controlling the inverter to terminate generating the first heating current and controlling to close the first connection switch, if the temperature of the power battery is less than a second temperature threshold, the method further includes:

controlling the motor to stop rotating to heat the power battery; or alternatively, the first and second heat exchangers may be,

and in the driving process, the power battery is heated by using the electric drive waste heat.

In practice, the first heating current may terminate heating the power cell for some reason (as described above). However, the temperature of the power battery is still relatively low, and there is a need for heating. Thus, the power battery may continue to be heated in other ways after the vehicle drive demand is met (control closes the first connection switch). For example, the power battery can be heated by blocking the motor, or the power battery is heated by using the electric drive waste heat, or the two modes of blocking the motor and heating the electric drive waste heat are mutually switched (for example, in the running process of the vehicle, the parking of the vehicle adopts the blocking heating of the motor, and the running of the vehicle adopts the heating of the electric drive waste heat). The termination condition of the heating mode may be selected and set according to needs, for example, when the heating time reaches the heating time length and reaches the time length threshold, or the temperature of the motor is greater than the third temperature threshold, or a termination heating instruction sent by a user, etc.

Optionally, the heating conditions are turned on further comprising at least one of: detecting that there is no occupant in the vehicle cabin; and/or, meeting a preset timing time for starting heating; and/or, when the vehicle is in a stopped state; and/or receiving a heating starting instruction sent by a user.

In practical application, as described above, when the first heating current is used to heat the power battery, whether to start heating can be determined according to the comprehensive conditions of the practical situation. Specifically, when the temperature of the power battery is lower than the first temperature threshold, the current power battery is indicated to have a heating requirement, and whether the look-up condition is met is further judged. The opening conditions described herein may be varied, including: the detection of no occupant in the vehicle cabin does not adversely affect the occupant's use experience even if large NVH noise is generated during the heating of the power cell with the first heating current. In addition, when the vehicle is in a stopped state, such as a vehicle stopped state (rather than waiting for a red light or the like to temporarily stop), it is also possible to indicate that there is no vehicle driving demand for a short period of time, and the power battery can be heated by the first heating current. Or, receiving the heating command from the user means that the user has a need for heating the power battery, and other negative effects (such as NVH noise generated by the first heating current) caused in the heating process of the first heating current are selectively ignored. Or, whether to start heating can be determined according to the timing time, for example, a user uses 7 hours a day in the morning, and in winter (that is, when the temperature of the power battery is lower than the first temperature threshold value), the heating is properly started according to the detected comprehensive estimation of the current temperature, the expected heating speed, the expected heating temperature and the like of the power battery, for example, when the current temperature of the power battery is-5 ℃, the first heating current is adopted for heating, namely, the heating needs to be started at 6 points; if the current temperature of the power battery is 5 degrees celsius, when the first heating current is used for heating, half an hour is needed, which means that the heating needs to be started separately at 6 points 30. So that less electrical energy is consumed while meeting the heating requirements.

Optionally, the first heating current is an alternating current, a frequency value of the first heating current is not greater than 50 hz, and the current frequency is a fixed frequency or a periodically varying frequency.

In practical applications, the frequency value of the first heating current is a low frequency value, for example, the low frequency value is not greater than 50 hz. The frequency value of the first heating current may be controlled as needed, for example, a fixed frequency value or a periodically variable frequency. By the method, the heating requirement is met, and other requirements (such as NVH reduction) are met.

In a second aspect, embodiments of the present application provide a battery heating system, the system comprising:

the controller is in communication connection with the power battery, the first connecting switch, the inverter and the motor; the first end of the power battery is respectively connected with the first end of the bus capacitor and the first end of the inverter, the second end of the power battery is respectively connected with the second end of the first connecting switch and the second end of the inverter, the first end of the first connecting switch is connected with the second end of the bus capacitor and the first end of the second connecting switch, and the second end of the second connecting switch is connected with the motor;

when the temperature is lower than a first temperature threshold value and the riding state is a passenger state, the first connecting switch is controlled to be opened, and the second connecting switch is controlled to be closed; controlling the inverter to generate a second heating current for heating the power battery;

when a heating termination condition is satisfied, the inverter is controlled to terminate generating the first heating current.

In a third aspect, embodiments of the present application provide a vehicle, including: a vehicle body and a power source;

the vehicle body is provided with a memory and a processor;

the memory is used for storing one or more computer instructions;

the processor is configured to execute the one or more computer instructions for performing the steps in the method of the first aspect.

In a fourth aspect, embodiments of the present application provide a computer-readable storage medium, which when executed is capable of implementing the steps in the method of the first aspect.

In the battery heating method, system, vehicle and medium provided by the embodiment of the application, a first connecting switch is connected in series in a circuit where a bus capacitor of a motor driving circuit is located, a first end of a second connecting switch is connected between the bus capacitor and the first connecting switch, and a second end of the second connecting switch is connected with a motor. When the temperature of the battery is lower than a first temperature threshold value, the battery is required to be heated, and the switching of the heating circuit and the driving circuit is realized by controlling the first connecting switch and the second connecting switch. When no occupant is present in the vehicle cabin, both the first connection switch and the second connection switch are turned off, that is, the bus capacitor is not included in the first heating circuit. After the heating circuit for heating the power battery is established, the heating circuit does not contain a bus capacitor, so that the electric energy consumption caused by the fact that heating current flows through the bus capacitor can be effectively avoided, and the heating efficiency and the electric energy effective utilization rate are improved. In addition, the heating circuit flowing through the heating circuit is controlled to be low-frequency current, and the internal resistance of the battery has the characteristic of large alternating current impedance to the low-frequency current under the low-temperature condition, so that the heating speed of the battery by using the low-frequency current is higher than the high-frequency heating speed, which means that the heating efficiency by using the low-frequency current is higher. And because the current flowing through the motor is low-frequency current, the consumption electric energy of the motor is lower than that of the high-frequency current, and the electric energy utilization rate is improved.

When passengers exist in the vehicle cabin, the first connecting switch is opened, the second connecting switch is closed, and the obtained second heating circuit comprises an inverter, a motor, a bus capacitor and a power battery, and the circuit is an LC resonant circuit. And heating the power battery in the current oscillation damping process. Because the second heating current is direct current, noise can not be generated when the second heating current flows through the motor, and the influence of NVH of the vehicle cabin on a user in the heating process is reduced while the heating requirement of the power battery is met.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:

FIG. 1 is a schematic diagram of a battery heating system illustrated herein;

FIG. 2 is a schematic diagram of a first target current regulation principle according to an embodiment of the present disclosure;

FIGS. 3a and 3b are schematic diagrams of first target current waveforms according to embodiments of the present application;

fig. 4 is a schematic flow chart of a battery heating method according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of a battery heating device according to an embodiment of the present disclosure;

Fig. 6 is a schematic structural diagram of a vehicle according to an embodiment of the present application;

FIG. 7 is a schematic diagram illustrating a flow of turning on a first heating current according to an embodiment of the present application;

FIG. 8a is a schematic diagram of a first heating circuit according to an embodiment of the present disclosure;

fig. 8b and 8c are schematic diagrams of a second heating circuit in a heating state according to an embodiment of the present application;

fig. 8d is a schematic diagram of the second heating circuit in a discharge state according to the embodiment of the present application.

Detailed Description

In order to enable those skilled in the art to better understand the present invention, the following description will make clear and complete descriptions of the technical solutions according to the embodiments of the present invention with reference to the accompanying drawings.

In some of the flows described in the description of the invention, the claims, and the figures described above, a number of operations occurring in a particular order are included, and the operations may be performed out of order or concurrently with respect to the order in which they occur. The sequence numbers of operations such as 101, 102, etc. are merely used to distinguish between the various operations, and the sequence numbers themselves do not represent any order of execution. In addition, the flows may include more or fewer operations, and the operations may be performed sequentially or in parallel. It should be noted that, the descriptions of "first" and "second" herein are used to distinguish different messages, devices, modules, etc., and do not represent a sequence, and are not limited to the "first" and the "second" being different types.

In the prior art, there are various related schemes for heating a vehicle battery, for example, the cooling liquid can be heated first, and then heat is transferred to the battery through the cooling liquid, and the external heating mode needs to consume battery electric energy to heat the cooling liquid first, so that the consumed electric energy of the battery cannot be completely transferred to the battery, and the electric energy utilization rate for heating is low. In addition, when the battery is heated, the battery is heated from outside to inside, the heating efficiency is low, and the battery is heated to the preset temperature for a long time. For example, when the battery is heated by using the internal resistance of the battery, the electric energy utilization rate during heating of the battery can be effectively improved compared with a mode of heating the battery by using the cooling liquid, but the electric energy is still consumed by non-relevant devices in the circuit, so that the electric energy utilization rate is not high, and the battery heating efficiency is low. Therefore, a solution capable of effectively improving the electric energy utilization efficiency and the heating efficiency when the battery is heated is needed.

The embodiment of the application provides a battery heating system. Fig. 1 is a schematic diagram of a battery heating system as exemplified in the present application. As can be seen from fig. 1, the system comprises: a controller 40, a power battery 10, a first connection switch 60, a second connection switch 61, an inverter 20, a motor 30, a bus capacitor 50, and the like. Specifically, the first connection switch 60 is connected in series with the bus capacitor 50, then connected in parallel with the power battery 10, and connected in parallel with the inverter 20. A first end of the second connection switch 61 is connected between the bus capacitor and the first connection switch 60, and each circuit of the inverter 20 is connected to each circuit of the motor 30. The inverter 20 is used for converting direct current provided by the power battery 10 into alternating current according with preset current parameters during driving. Here, the heating current is a current for heating the power battery 10, not a current for driving the motor to rotate, and thus, the preset current parameter satisfies the heating requirement while minimizing excessive consumption of electric energy by the motor (e.g., avoiding the generation of eddy current to consume electric energy). The setting and use of preset current parameters will be described in connection with specific embodiments.

During use, the circuits in the system are adjusted as needed. Specifically, when there is a need for heating the power battery (for example, when the target temperature of the current battery is detected to be less than the first temperature threshold value, it indicates that the power battery needs to be heated), and no passenger exists in the cabin, the first connection switch and the second connection switch are controlled to be turned off, and a heating circuit is established. As shown in fig. 1, the controller 40 controls the first connection switch 60 to be turned off, and at this time, the circuit of the bus capacitor 50 is broken, and no current flows through the circuit of the bus capacitor. The first heating current is used for supplying power to the power battery 10 through the power battery 10, the inverter 20 and the motor 30 in sequence, and a complete heating circuit is formed by the power battery 10.

The operation of the heating circuit will be described below.

A temperature sensor is also included in the system for sensing the temperature of the power cell. The temperature sensor may be a sensor built in the battery (e.g., a sensor built in between two cells) so that the temperature of the battery is more accurate. In addition, the first temperature threshold of the power battery can be adjusted according to requirements, for example, the current ambient temperature, the residual power of the power battery and the like are comprehensively considered, and how the first temperature threshold is set. For example, in the case where the ambient temperature is low and the remaining power of the power battery is sufficient, the first temperature threshold may be set to a higher temperature; on the contrary, under the condition that the approximate ambient temperature is not low and the residual electric quantity of the power battery is not enough, the first temperature threshold is set to be lower, and a small amount of electric energy is consumed to improve the power supply capacity of the power battery.

In addition, the temperature of the power battery may be the temperature in the coolant/lubricant for cooling the battery, and the sensor may be disposed in the battery cell, in the battery pack, in contact with the battery cell, in contact with the liquid for cooling the battery pack, in contact with the battery pack outside the battery pack, in contact with the liquid for cooling the battery pack, and the like. The detection positions when detecting the battery are different, and the corresponding first temperature thresholds may also be different.

When the current temperature of the power battery is smaller than a first temperature threshold value, the controller controls the first connection switch to be opened, and controls the inverter to provide a first heating current (the first heating current is a low-frequency current by default) for the power battery in the heating circuit, so that the power battery can generate heating heat by using the first heating current.

The heating current here is a low frequency current, the frequency of which here may be, for example, between 10Hz and 50 Hz. Because the internal resistance of the power battery has the characteristic of large alternating current impedance under the condition of low temperature, the low-frequency current is higher than the high-frequency current heating efficiency under the condition of the same heating current, and the heating speed of the power battery is higher.

In addition, eddy current losses are generated in the rotor due to the heating current required to flow through the motor. Therefore, in the case of low-frequency current, the eddy current generated in the rotor is relatively small, the rotor of the motor does not have obvious temperature rise in the process of heating the power battery, the motor consumes little electric energy in the heating process, in other words, the long-time heating current can be allowed to flow through the motor and heat the power battery.

When low-frequency current (namely first heating current) flows through the motor, the gear in the motor is knocked to generate noise, so that the motor is not friendly to personnel in a cabin, and the personnel use experience is poor. Therefore, if an occupant is in the vehicle cabin, a higher frequency of current than the first heating current may be used to heat the power battery depending on the occupant's needs. When heating by high frequency current, it should be noted that when the high frequency first heating current flows through the motor, a significant eddy current effect is generated, in other words, the heat loss generated by the high frequency heating current flowing through the motor is significantly greater than the heat generated by the low frequency heating current flowing through the motor. Therefore, the power battery cannot be heated using the high-frequency heating current for a long time. The specific heating method will be specifically described in the following examples, and the detailed description will not be repeated here.

In addition, the first connecting switch is disconnected, and the bus capacitor and the power battery are not in electrical connection, namely the first heating current does not flow through the bus capacitor, which means that the electric energy cannot be consumed by the bus capacitor, so that the battery heating efficiency and the effective utilization rate of the first heating current are effectively improved.

In practical applications, the current may be dynamically adjusted using the controller and the inverter in order to enable the first heating current to be more fully used for battery heating. Specifically, when the first connection switch is turned off, the controller transmits an inversion control signal generated based on a preset current parameter to the inverter through a communication connection manner so as to supply a first heating current to the motor.

Fig. 2 is a schematic diagram of a first heating current regulation principle according to an embodiment of the present application. As can be seen from fig. 2, the initial current Idc-rms supplied from the power battery is input, and the current having the frequency and amplitude corresponding to the current frequency and current amplitude is output through PI adjustment, and flows to the motor. Meanwhile, the feedback current of the motor is only collected, and a heating current feedback value Idc-fdk is obtained. Further, the initial current Idc-rms and the heating current feedback value Idc-fdk are compared to obtain the adjustment value Δidc and input to PI adjustment. By means of fig. 2, a dynamic regulation process for outputting the first heating current can be obtained. And the control algorithm of the pulse heating function adjusts the frequency and amplitude of the low-frequency Idc in real time, so that closed-loop control is realized.

The first heating current, that is, the pulse current Idc flowing through the dc bus: the alternating d-axis current is led into the three-phase coil of the motor through the switching tube of the power module of the controller, and the principle of energy storage and release of the inductance of the three-phase coil is utilized, so that the pulse current with positive and negative alternating changes is generated at the DC bus end. And (3) pulse heating of a battery: the pulse current with alternately changed positive and negative bus ends flows through the battery to make the battery in a reciprocating charge and discharge state, and meanwhile, the pulse current acts on the internal resistance of the battery to directly heat the battery cell in an ohmic heating mode. The heating mode using ohmic heating is different from external heating, and has high electric energy utilization rate, high heating efficiency and high heating speed.

The preset current parameters include: at least one of current amplitude, current frequency, amplitude period, frequency period, and current waveform.

The first heating current is here an alternating current, which, as mentioned above, is a low frequency current, corresponding to a current frequency of not more than 50 hz. In practical applications, the current frequency may be a fixed frequency or a periodically varying frequency. The following will illustrate by way of specific examples.

Fig. 3a and 3b are schematic diagrams of a first heating current waveform according to an embodiment of the present application.

The heating current waveform shown in fig. 3a is a waveform diagram with a constant current amplitude and a variable frequency, a low-frequency (10-50 Hz) current with a constant current amplitude and a periodically-changed current frequency is input to the d-axis of the motor, and the current waveform of the low-frequency exciting current can be d-axis exciting current Id of a sine wave or square wave and other waveforms. The low-frequency current Idc is generated on a direct-current bus of the inverter, the Idc flows through the power battery to generate ohmic heat to heat the power battery, and the original concentrated radial electromagnetic force is uniformly dispersed on the whole stator by introducing more frequency components (for example, a square wave contains a low-frequency fundamental wave or a sine wave periodically changes frequency), so that vibration noise in the heating process of the power battery is greatly reduced.

A heating current waveform shown in fig. 3b is a waveform diagram with a variable current amplitude and a variable frequency, the current amplitude is periodically changed and the current frequency is periodically changed in a low-frequency (10-50 Hz) current, and the current waveform of the low-frequency exciting current can be d-axis exciting current Id of a sine wave or square wave and other waveforms. The low-frequency current Idc is generated on a direct-current bus of the inverter, the Idc flows through the power battery to generate ohmic heat to heat the power battery, and the original concentrated radial electromagnetic force is uniformly dispersed on the whole stator by introducing more frequency components (for example, a square wave contains a low-frequency fundamental wave or a sine wave periodically changes frequency), so that vibration noise in the heating process of the power battery is greatly reduced.

When the first connecting switch is closed under the condition that the battery is not required to be heated, a driving circuit is formed by the power battery, the bus capacitor, the first connecting switch, the inverter and the motor; specifically, the first connection switch 60 is connected in series with the bus capacitor 50, then connected in parallel with the power battery 10, and connected in parallel with the inverter 20. The respective circuits of the inverter 20 are connected to the respective circuits of the motor 30. And an inverter 20 for converting direct current supplied from the power battery 10 into driving current for driving the motor to rotate, thereby supplying driving force to the vehicle.

If the heating termination condition is met, controlling the inverter to terminate generating the first heating current, and controlling the first connecting switch to be closed; wherein the heating termination condition includes at least: the detected temperature of the power cell is greater than a second temperature threshold.

In particular, when the current battery temperature is detected to be greater than the second temperature threshold, this indicates that heating of the power battery is no longer required,

alternatively, a driving circuit including a bus capacitor may be established by controlling the first connection switch to be closed. As shown in fig. 1, the controller 40 controls the first connection switch 60 to be closed, and at this time, the circuit where the bus capacitor 50 is located is connected, and current can flow through the circuit where the bus capacitor is located. The drive current will power the motor via the sequence of the power battery 10, the inverter 20 and the motor 30. The driving circuit which meets the driving requirement simultaneously is realized through the first connecting switch under the condition that the traditional motor driving circuit is not required to be changed excessively and the hardware cost is not obviously increased, and the two effects of motor driving and battery heating can be realized simultaneously by switching the battery heating circuit which meets the battery heating requirement.

The inverter is also configured to generate a torque current that meets a torque current parameter. Specifically, a small current which is not zero is input to the q-axis through the inverter, so that small understanding can be generated, a motor gear can lean on one side, and the problem of noise generated by characteristic frequency resonance of the moment zero-crossing whole vehicle due to gear clearance tooth punching is avoided. The torque current Iq is smaller than a first preset current threshold value, so that the motor generates a first moment, and the first moment is smaller than the first preset moment threshold value; i.e. the first moment does not cause the motor to rotate.

Based on the same thought, the embodiment of the application provides a battery heating method. Fig. 4 is a schematic flow chart of a battery heating method according to an embodiment of the present application. The execution subject of the method may be a vehicle-mounted controller. As can be seen from fig. 4, the method comprises the steps of:

the battery heating method is applied to a controller of a battery heating system, and the battery heating system comprises the following steps: the controller is respectively in communication connection with the power battery, the first connecting switch, the inverter and the motor; the first end of the power battery is respectively connected with the first end of the bus capacitor and the first end of the inverter, the second end of the power battery is respectively connected with the second end of the first connecting switch and the second end of the inverter, the first end of the first connecting switch is connected with the second end of the bus capacitor and the first end of the second connecting switch, and the second end of the second connecting switch is connected with the motor;

The method comprises the following steps:

step 401: a temperature indicative of the power cell and a seating condition of an occupant in a vehicle cabin are obtained.

Step 402: when the temperature is lower than a first temperature threshold value and the riding state is an unoccupied state, the first connection switch and the second connection switch are controlled to be disconnected; the inverter is controlled to generate a first heating current for heating the power battery.

Step 403: when the temperature is lower than a first temperature threshold value and the riding state is a passenger state, the first connecting switch is controlled to be opened, and the second connecting switch is controlled to be closed; the inverter is controlled to generate a second heating current for heating the power battery.

In practical application, a proper power battery heating mode is selected by comprehensively considering the temperature of a battery and the riding state of passengers in a vehicle cabin. Specific examples are:

fig. 8a is a schematic diagram of a first heating circuit according to an embodiment of the present application. When heating is needed (namely, when the temperature of the battery is lower than a first temperature threshold value) and no passenger sits in the vehicle cabin, the first heating current which does not need to flow through the bus capacitor can be utilized to heat the power battery, and the heating efficiency and the electric energy utilization rate can be effectively improved. In the first heating circuit, the first connection switch and the second connection switch are disconnected, and the bus capacitor is in a disconnected state at this time, that is, the first heating current does not flow through the bus capacitor. This enables efficient heating with the first heating current. The specific implementation may refer to the embodiment corresponding to step 4021, and the detailed description will not be repeated here.

Fig. 8b and 8c are schematic diagrams of the second heating circuit in a heating state according to the embodiment of the present application. If a passenger sits in the vehicle cabin, the power battery is heated by the second heating current in order to avoid noise generated during the heating process and to influence the riding experience of the passenger. In the heating process, the heating requirement and the riding experience requirement of the passengers can be simultaneously met. In the second heating circuit, the first connecting switch is opened, the second connecting switch is closed, the power battery, the inverter, the motor and the bus capacitor jointly form a second heating circuit, and in the heating circuit, the equivalent inductance of the motor and the bus capacitor jointly form an LC resonance circuit. Because in this circuit, the second heating current is direct current, can not produce alternating magnetic field in the motor, just means no torque ripple produces yet, and motor rotor can not rotate, and whole NVH performance is better, and the passenger can obtain better riding experience. Fig. 8b is a schematic diagram showing an energy storage state in the LC resonant circuit, fig. 8c is a schematic diagram showing an energy release state in the LC resonant circuit, in which the current in the LC resonant circuit can store and release energy for multiple times during a heating period, and the power battery is heated in the process of storing and releasing energy for multiple times.

Specifically, the controlling the inverter to generate a second heating current for heating the power battery includes: controlling a first switching device group in the inverter to be opened and controlling at least one switching device in a second switching device group to be closed so that the second heating current flows through the bus capacitor, the motor and the power battery in a heating period; wherein the second heating current is a direct current.

In practical application, the second switching device 61, the bus capacitor 50, the motor 30 and the power battery 10 together form a second heating circuit, and in the second heating circuit, the bus capacitor and an equivalent inductance in a three-phase winding in the motor together form an LC resonant circuit. In the process of charging and discharging the bus capacitor and the equivalent inductor, the heating of the power battery is realized. It should be noted that the inverter includes two sets of switching devices, the first set of switching devices includes S1, S3, and S5, the second set of switching devices includes S2, S4, and S6, and the switching devices S1 and S2 are connected to a first phase in the motor, the switching devices S3 and S4 are connected to a second phase in the motor, and the switching devices S5 and S6 are connected to a third phase in the motor. When heating with the second heating current, S1, S3, S5 in the first switching device group are all open, and S2, S4, S6 in the second group are at least 1 closed. Of course, any two, or all three, of them may be closed as desired. When 1 switching device is closed, it means that only one direct current flows through the second heating circuit to heat the power battery; when 2 switching devices are closed, this means that there are two paths of current flowing through the second heating current after the motor merges to heat the power battery.

In general, in order to improve the heating efficiency, three switching devices in the second switching device group are closed at the same time, which is specifically described as follows:

the controlling the opening of the first switching device group in the inverter and the closing of at least one switching device in the second switching device group comprises the following steps: and if the first switching device group in the inverter is controlled to be opened, and the three switching devices in the second switching device group are controlled to be closed, the power battery is connected with the three switching devices, the three windings in the motor and the bus capacitor, so that the second heating current is generated by three-phase direct current flowing through the three switching devices and the three windings.

The inverter is used for converting direct current into three-phase alternating current, switching devices in the inverter can be divided into two groups, and each group has 3 switching devices, namely S2, S4 and S6. Three paths of direct current of the 3 switching devices respectively flow through three-phase windings of the motor, namely, three-phase direct current simultaneously flows through the motor windings, no phase difference exists between currents in the three-phase windings, the three-phase direct current is zero sequence current, no 120-degree phase difference exists, high-frequency eddy current loss cannot be generated on a rotor, magnetic steel generates less heat, and the duration time of heating is allowed to be longer. Meanwhile, the alternating magnetic field is not generated in the rotor of the motor, and no torque pulsation is generated, so that the NVH performance of the vehicle is better. In addition, the heating current flowing through the power battery is approximately equal to the sum of three-phase currents of the motor, and when the motor side currents are the same, the heating current flowing through the power battery is larger, and the battery temperature rise speed is higher.

Fig. 8d is a schematic diagram of the second heating circuit in a discharge state according to the embodiment of the present application. As shown in fig. 8d, the second switching device group is controlled to be opened, and at least one switching device in the first switching device group is controlled to be closed, so as to generate a discharging circuit comprising the inverter, the motor and the bus capacitor, so as to release electric energy in the bus capacitor in a discharging period.

In practical application, since the electric charge is repeatedly oscillated in the second heating circuit in the heating period, the electric charge is gradually consumed in the oscillation process, so that the second heating current is gradually reduced, and the heating capacity is gradually reduced. At this time, it is necessary to discharge the charge on the capacitor, that is, to establish a discharge circuit, to open each switching device in the second switching device group, and to close the corresponding switching device in the first switching device, thereby generating a discharge circuit including the bus capacitor, the motor, and the inverter. That is, at least one of the switching devices S1, S3, S5 is closed, and at the same time, the switching devices in the second switching device are all opened, so that the first switching device group, the motor and the capacitor together form a discharge circuit. After the excess charge in the capacitor is discharged, the above steps are repeated, i.e. at least one switching device of the second switching device group is turned off and all switching devices of the first switching device group are turned off.

The switching device closed by the energy storage and release of the second heating circuit corresponds to the switching device closed during the discharging process. Specifically, when switching device S2 is closed during the heating period, switching device S1 should be closed during the discharging period; if switching device S4 is closed during the heating period, switching device S3 should be closed during the discharging period. If the switching devices S2, S4, S6 are closed during the heating period, the switching devices S1, S3, S5 should be closed during the discharging period. Thereby enabling a more efficient and thorough discharge.

Optionally, the heating period is greater than the discharge period. In practical application, in order to improve the heating efficiency of the power battery, the inverter is controlled to operate according to the heating period and the discharging period when the power battery is heated by the second heating circuit and the second heating current. Since the amount of charge in the capacitor is not much during discharging, the discharging task can be completed in a short time. Therefore, during the heating process, it is necessary to ensure that the heating period is greater than the discharging period, that is, the duty cycle of the second switching device group is greater than the duty cycle of the first switching device when the duty cycle of each switching device in the inverter is controlled.

As an alternative embodiment, each switching device in the inverter comprises a second switching period group S2/S4/S6 and a first switching device group S1/S3/S5, and the switching frequency is high (f is more than or equal to 8000 Hz), wherein the duty ratio of S2/S4/S6 in the second switching device group is more than or equal to 90%, and the duty ratio of S1/S3/S5 in the first switching device group is less than or equal to 10%. But this duty cycle is not fixed and can be adjusted according to the actual needs. For example, a second heating current target value Idc of the battery is set, three-phase current flowing through the motor is sampled in real time, a battery heating current feedback value fdk is estimated by the three-phase current, and the second heating current target value is differed from the battery heating current feedback value Idc-fdk to obtain the adjustment value Δidc. The adjustment value is input into a PI adjuster for closed-loop adjustment, the PI adjuster adjusts the switching frequency and the duty ratio of the output S2/S4/S6 through an internal algorithm, and the second heating current Idc of the battery is adjusted in real time according to the switching frequency and the duty ratio of the output S2/S4/S6.

The controlling the inverter to generate a first heating current for heating the power battery includes:

step 4021: controlling the inverter to generate a first heating current, wherein the first heating current does not flow through the bus capacitor after the first connecting switch is disconnected, so that the power battery is heated by the first heating current; wherein the first heating current is a low frequency current less than a specified frequency threshold.

In the motor drive control circuit, when the battery temperature is low, it is necessary to heat the battery. The controller controls the first connection switch and the second connection switch to be turned off, thereby generating a heating power supply circuit not including the bus capacitor, and since the heating current does not need to flow through the bus capacitor, the heating current is not consumed by the bus capacitor. The heating power supply circuit generates heating current which accords with preset current parameters, the preset current parameters have low current frequency (for example, 10 Hz to 50 Hz), and under the low-temperature condition, the internal resistance of the battery has the characteristic of large alternating current impedance of low-frequency current, so that the heating speed of the battery by using the low-frequency current is higher than that of the battery by using the low-frequency current, namely, the heating efficiency by using the low-frequency current is higher. In addition, because the current flowing through the motor is low-frequency current, the consumption electric energy of the motor is lower than that of the high-frequency current, and the electric energy utilization rate is improved.

When the heating termination condition is met, for example, the vehicle is started, or the heating temperature meets the set temperature, the working state of the first connecting switch is controlled by the controller to be adjusted to be in a closed state, and meanwhile, the second connecting switch is kept in an open state. After the first connection switch is adjusted to the closed state, a driving circuit is generated. Further, the drive control of the vehicle can be achieved by controlling the drive current flowing through the drive circuit to drive the motor. The battery power supply effect can be effectively improved.

In one or more embodiments of the present application, when the temperature of the power battery is lower than a first temperature threshold, a heating circuit for heating the power battery is generated, and a first heating current for heating the power battery in the heating circuit is generated, as illustrated in fig. 7, which is a schematic flow diagram of turning on the first heating current in the embodiment of the present application. The method specifically comprises the following steps:

step 701: and acquiring the position relation between the personnel and the vehicle.

Step 702: and when the temperature of the power battery is lower than a first temperature threshold value, generating a heating circuit for heating the power battery.

Step 703: and when the position relation is that the person is in the vehicle cabin, generating a second direct-current heating current to heat the power battery in the heating circuit.

Step 704: and when the position relation is that the person is not in the vehicle cabin, generating a low-frequency first heating current to heat the power battery in the heating circuit.

In practical application, after the current temperature is obtained by detecting the temperature of the power battery of the vehicle, whether the current temperature of the power battery is lower than a first temperature threshold value is judged. If the current temperature of the power battery is lower than the first temperature threshold value, the power battery needs to be heated, and therefore the driving circuit needs to be adjusted to be heated by the heating circuit. When heating is performed, a combination of battery heating efficiency (i.e., the rate of temperature rise of the same current heating power battery) and vehicle noise, vibration and harshness (Noise, vibration, harshness, NVH) are required.

Specifically, when a person (such as a driver, a passenger, or the like) is not in the cabin, it is necessary to realize the power battery heating in a high-efficiency, fast, low-consumption manner, and at this time, the battery is heated by the first heating current of low frequency (for example, 10HZ to 50 HZ) by utilizing the characteristic that the ac impedance of the internal resistance of the power battery is large at the low temperature of the battery under the low frequency current, so that the optimal heating effect can be obtained. However, because the first heating current adopts a low frequency value, when the first heating current flows through the motor in the heating circuit, the first heating current is alternating current, and when the first heating current flows through the motor, the motor can generate rotor knocking action due to low frequency change of current flow direction, so that knocking sound which can be perceived by personnel is generated, and in order to avoid obvious influence on the use experience of personnel in a cabin caused by NVH of a vehicle, the second heating current is adopted to heat the power battery. The heating requirement is met while the use experience of the user is ensured.

In one or more embodiments of the present application, when the power battery in the heating circuit is heated by using a low-frequency first heating current, if status information of entering a cabin by a person is received, a frequency value of the first heating current is increased, so as to obtain a first target current applied to the first heating circuit.

In practical application, if the current power battery is heated by the low-frequency first heating current, a high-efficiency heating effect can be obtained, but because the frequency value of the first heating current is low, obvious noise can be generated when the current flows through the motor of the heating circuit. Thus, in case a person enters the vehicle, the first heating current parameter is adjusted in time, e.g. the frequency value is increased, e.g. from 50 hz to 1000 hz. The heating requirement is met, the disturbance to the user in the heating process of the power battery is avoided or reduced, and the use experience of the user in the cabin is ensured. Among them, there are various ways of determining that a person enters the cabin, such as various ways of opening a door, detecting that a vehicle key is approaching, unlocking a vehicle, and the like. Of course, it is also possible to detect the occupant's seating condition in the cabin, the position in the cabin, or the occupant's seating condition in the cabin with a camera, using a seat-mounted seat belt sensor. When the heating current frequency is increased, the target frequency value may be directly adjusted, or a high-frequency current of other frequencies that do not generate significant motor noise may be adjusted as needed.

In one or more embodiments of the present application, after generating a first target current to heat the power battery in the heating circuit, further comprising: determining a second temperature threshold at which the power battery terminates heating, and a temperature threshold of the motor; and when the temperature of the power battery is obtained to be greater than the second temperature threshold value, or when the temperature of the motor is obtained to be greater than the third temperature threshold value, terminating the first heating current.

The second temperature threshold is a temperature threshold for determining whether the power battery is terminated to be heated, that is, heating is stopped when the temperature for heating the power battery reaches the second temperature threshold. Meanwhile, since the first target current is high-frequency current, the temperature of the motor is obviously raised when the first target current flows through the motor, the temperature of the motor needs to be monitored, and when the temperature of the motor reaches a third temperature threshold value, the heating needs to be stopped.

In practical application, when the power battery is heated by the high-frequency first heating current, the first heating current has higher current frequency, and when the first heating current flows through the motor, although the noise of the motor can be effectively avoided or reduced by the high-frequency first heating current, the eddy current effect generated by the high-frequency current in the motor is more obvious than that generated by the low-frequency current when the low-frequency current flows through the motor, in other words, when the power battery is heated by the high-frequency first heating current, the motor can be quickly heated under the action of the eddy current effect, the motor can waste the electric energy of the power battery, and the motor can be damaged if the temperature is too high. Therefore, the temperature of the power battery is monitored, and the temperature of the motor is also required to be monitored under the condition of heating by the first heating current. Whether the temperature of the power battery reaches the second temperature threshold value or the motor reaches the third temperature threshold value, the heating of the power battery is stopped immediately; i.e. to terminate the output of the first heating current.

For example, the power cell is heated with a first heating current while the person is in the cabin. As the heating proceeds, the temperature of the power battery gradually increases, and at the same time, the temperature of the motor also increases. Assume that the second temperature threshold is 0 degrees celsius and the third temperature threshold is 150 degrees celsius. Because the high-frequency first target current is adopted to heat the motor, the temperature rising speed of the motor is obviously faster than that of the power battery, the temperature of the power battery can not reach 0 ℃, but the temperature of the motor reaches 150 ℃. Therefore, if the power battery is heated by the first heating current, the power battery temperature and the motor temperature need to be monitored simultaneously.

In one or more embodiments of the present application, when the low-frequency first heating current is used to heat the power battery, the eddy current effect is significantly lower than that generated by the high-frequency first heating current when the first heating current flows through the motor, in other words, when the low-frequency first heating current is used to heat the power battery, the motor will not be significantly heated under the effect of the eddy current effect, and the temperature of the motor caused by the low-frequency first heating current is negligible. Therefore, in the heating process, only the heating temperature of the power battery is required to be monitored in real time, and the temperature of the motor is not required to be monitored. When the temperature of the power battery reaches the second temperature threshold value, the inverter is controlled to stop generating heating current, and heating of the power battery is stopped. Other adverse effects brought in the heating process can be avoided while the heating requirement is met.

In one or more embodiments of the present application, the controlling the first connection switch to be opened includes:

and the first connecting switch is controlled to be disconnected, the first end of the power battery is connected with the first end of the inverter, and the second end of the power battery is connected with the second end of the inverter, so that the first heating current flows through a heating circuit comprising the power battery, the inverter and the motor.

In the motor drive control circuit, when the battery temperature is low, it is necessary to heat the battery. The controller controls the first connecting switch to be disconnected, so that a heating circuit without the bus capacitor is generated, and the first heating current does not need to flow through the bus capacitor, so that electric energy cannot be consumed by the bus capacitor, and the heating efficiency of the power battery can be effectively improved. The low frequency (for example, 10 hz to 50 hz) has the characteristic that the internal resistance of the battery is large in alternating current impedance to the low frequency current under the low temperature condition, so that the heating rate of the battery by using the low frequency current is higher than that of the battery by using the high frequency current under the condition that the current is the same, which means that the heating efficiency by using the low frequency current is higher. In addition, because the current flowing through the motor is low-frequency current, the consumption electric energy of the motor is lower than that of the high-frequency current, and the electric energy utilization rate is improved.

The heating termination condition further includes at least one of: the detected temperature of the motor is greater than a third temperature threshold; and/or, the heating duration of the first heating current reaches a duration threshold; and/or receiving a vehicle driving instruction; and/or receiving a heating termination instruction sent by a user.

In practical applications, there are a plurality of conditions for stopping heating, and in addition to the second temperature threshold and the third temperature threshold, the heating time may be set (for example, the heating time may be set to 20 minutes after the user starts the vehicle for 20 minutes). In addition, the vehicle can be selected according to the working state of the vehicle, for example, when a user starts the vehicle in a cabin, or remotely starts the vehicle, or when the user sends a heating termination instruction, the heating of the power battery is terminated, the first connecting switch is controlled to be closed, the bus capacitor is connected into the driving circuit, and the inverter is controlled to provide driving current. Still alternatively, the first heating current may need to flow through the motor, creating eddy currents in the motor, causing the motor to warm up. Therefore, in order to avoid damage to the motor, the temperature of the motor needs to be monitored during the heating of the battery. When the controller finds that the temperature of the motor is greater than the third temperature threshold, it considers that the motor safety temperature range is exceeded, and the heating needs to be stopped. In the scheme, the controller controls the inverter to work to generate heating current and driving current with various frequencies and magnitudes. The motor is prevented from being damaged due to overhigh temperature while the heating requirement of the battery is met. Through the mode, the heating requirement of the power battery is met, and meanwhile, the heating can be stopped timely and the driving state can be switched to according to the requirement, so that the rapid switching of the heating circuit and the driving circuit is realized.

For example, assume that the set time is 10 minutes, since the driver gets on the vehicle after 10 minutes. Then after the timing reaches 10 minutes, the heating of the battery is stopped and the driver waits for the vehicle to drive. Or when the driver is detected to sit in the cab or an obvious driving request such as gear adjustment of the driver is detected, the battery is immediately stopped from being heated, and the battery is controlled to supply power to the motor so as to meet driving requirements.

Optionally, the method further comprises: after the first target current is stopped, the first connecting switch is controlled to be closed, and the inverter is controlled to supply power to the driving circuit so as to drive the motor to rotate through the driving circuit.

Optionally, the first heating current is an alternating current, the specified frequency threshold is not greater than 50 hz, and the current frequency is a fixed frequency or a periodically varying frequency.

In practice, the first heating current is a low frequency current, for example, the low frequency value is not greater than 50 hz. The frequency value may be controlled as needed, for example, a fixed frequency value or a frequency that varies periodically. By the method, the heating requirement is met, and other requirements (such as NVH reduction) are met.

Optionally, the inverter is further configured to generate the first heating current that meets a torque current parameter.

In order to facilitate understanding of the following description by way of specific examples, the following examples will illustrate the use of a low frequency first heating current.

By default, the first connection switch 60 is in a closed state, i.e. the drive circuit is in an active state, and the heating circuit is in an inactive state. When it is desired to heat the battery, the controller controls the first connection switch 60 to be turned off. A constant torque current Iq is input to the q-axis of the motor after adjustment via the inverter, and is less than a current threshold to ensure that the motor generates a torque less than a preset torque threshold (i.e., less than the torque required to rotate the motor) and that the motor does not rotate. A low-frequency first heating current is input to the d-axis of the motor, the current amplitude of the current is variable and fixed, and the current frequency of the current is variable and fixed. It is noted, however, that it is ensured that the current frequency is not too high, i.e. that the heating current is a low frequency current (e.g. a frequency between 10 hz and 50 hz). The current waveform may be a sine wave, square wave, or the like. The DC bus of the inverter generates low-frequency current Idc, and the low-frequency current Idc flows through the power battery to generate ohmic heat for heating the power battery.

When a sinusoidal current is used,where Is the maximum allowable motor phase current and Iq Is the q-axis current. Assuming that the target value of the first heating current provided for heating the battery is Idc, sampling three-phase current of the motor in real time, estimating a feedback value Idc-fdk of the heating current of the battery through the three-phase current, and obtaining an adjustment value Δidc by differentiating the first heating current from the feedback value. And inputs the adjustment value into the PI regulator to perform closed loop adjustment of the first heating current. Further, the PI regulator outputs a current of a low frequency sine wave or a low frequency square wave through a preset control algorithm, and the frequency, amplitude, period and waveform of the low frequency current heat the battery.

Based on the same thought, the embodiment of the application also provides a battery heating device. Fig. 5 is a schematic structural diagram of a battery heating device according to an embodiment of the present application. As can be seen from fig. 5, the device comprises:

The method comprises the following steps:

an acquisition module 51 for acquiring a temperature representative of the power battery and a seating state of an occupant in the vehicle cabin.

A control module 52 for controlling the first and second connection switches to be turned off when the temperature is lower than a first temperature threshold and the seating state is an unoccupied state; the inverter is controlled to generate a first heating current for heating the power battery.

The control module 52 is configured to control the first connection switch to be opened and the second connection switch to be closed when the temperature is lower than a first temperature threshold and the seating state is an occupant state; the inverter is controlled to generate a second heating current for heating the power battery.

A control module 52 for controlling the opening of the first switching device group in the inverter and the closing of at least one switching device in the second switching device group so that the second heating current flows through the bus capacitor, the motor and the power battery during a heating period; wherein the second heating current is a direct current.

And a control module 52, configured to control the first switching device group in the inverter to be opened and control the three switching devices in the second switching device group to be all closed, wherein the power battery is connected to the three switching devices, the three windings in the motor, and the bus capacitor, so as to generate the second heating current from the three-phase direct current flowing through the three switching devices and the three windings.

And a control module 52, configured to control the second switching device group to be opened and control at least one switching device in the first switching device group to be closed, so as to generate a discharge circuit including the inverter, the motor and the bus capacitor, so as to release electric energy in the bus capacitor in a discharge period.

Optionally, the heating period is greater than the discharge period.

The control module 52 is configured to control the inverter to generate a first heating current, and after the first connection switch is turned off, the first heating current does not flow through the bus capacitor, so that the power battery is heated by using the first heating current; wherein the first heating current is a low frequency current less than a specified frequency threshold.

Optionally, the control module 52 is further configured to control the inverter to terminate generating the first heating current and control the first connection switch to be closed if a heating termination condition is satisfied; wherein the heating termination condition includes at least: the detected temperature of the power cell is greater than a second temperature threshold.

The control module 52 is configured to control to disconnect the first connection switch, a first end of the power battery is connected to the first end of the inverter, and a second end of the power battery is connected to the second end of the inverter, so that the first heating current flows through a heating circuit including the power battery, the inverter, and the motor.

Optionally, if the temperature of the power battery is less than a second temperature threshold, the control module 52 is further configured to control the motor to stop rotating to heat the power battery; or, in the driving process, the power battery is heated by using the electric drive waste heat.

Optionally, the first heating current is an alternating current, the specified frequency threshold is 50 hz, and the alternating current is a fixed frequency or a periodically varying frequency.

Fig. 6 is a schematic structural diagram of a vehicle according to an embodiment of the present application, where, as shown in fig. 6, a vehicle device is configured on the vehicle, and the vehicle device includes: a memory 601 and a controller 602.

The memory 601 is used for storing computer programs and may be configured to store other various data to support operations on the vehicle device. Examples of such data include instructions for any application or method operating on the vehicular device, contact data, phonebook data, messages, pictures, videos, and the like.

The Memory 601 may be implemented by any type or combination of volatile or non-volatile Memory devices, such as Static Random-Access Memory (SRAM), electrically erasable programmable Read-Only Memory (Electrically Erasable Programmable Read Only Memory, EEPROM), erasable programmable Read-Only Memory (Electrical Programmable Read Only Memory, EPROM), programmable Read-Only Memory (Programmable Read-Only Memory, PROM), read-Only Memory (ROM), magnetic Memory, flash Memory, magnetic disk, or optical disk.

The vehicle apparatus further includes: a display device 603. A controller 602 coupled to the memory 601 for executing a computer program in the memory 601 for:

The method comprises the following steps:

The controller 602 is configured to control the first switching device group in the inverter to be opened and control at least one switching device in the second switching device group to be closed, so that the second heating current flows through the bus capacitor, the motor and the power battery during a heating period; wherein the second heating current is a direct current.

The controller 602 is configured to control the first switching device group in the inverter to be opened and control the three switching devices in the second switching device group to be all closed, and the power battery is connected to the three switching devices, the three windings in the motor, and the bus capacitor, so as to generate the second heating current from the three-phase direct current flowing through the three switching devices and the three windings.

The controller 602 is configured to control the second switching device group to be opened and control at least one switching device of the first switching device group to be closed, and generate a discharge circuit including the inverter, the motor, and the bus capacitor, so as to release electric energy in the bus capacitor during a discharge period.

The heating period is greater than the discharge period. Controlling the inverter to generate a first heating current, wherein the first heating current does not flow through the bus capacitor after the first connecting switch is disconnected, so that the power battery is heated by the first heating current; wherein the first heating current is a low frequency current less than a specified frequency threshold.

The controller 602 is configured to control the inverter to terminate generating the first heating current and control the first connection switch to be closed if a heating termination condition is satisfied; wherein the heating termination condition includes at least:

The controller 602 is configured to control to disconnect the first connection switch, a first end of the power battery is connected to a first end of the inverter, and a second end of the power battery is connected to a second end of the inverter, so that the first heating current flows through a heating circuit including the power battery, the inverter, and the motor.

The heating termination condition further includes at least one of:

the detected temperature of the motor is greater than a third temperature threshold; and/or the number of the groups of groups,

the heating time length of the first heating current is used for reaching a time length threshold; and/or the number of the groups of groups,

receiving a vehicle running instruction; and/or the number of the groups of groups,

detecting that an occupant is in the vehicle cabin; and/or the number of the groups of groups,

and receiving a heating termination instruction sent by a user.

After controlling the inverter to stop generating the first heating current and controlling to close the first connection switch, if the temperature of the power battery is less than a second temperature threshold, the controller 602 is configured to control the motor to stop rotating to heat the power battery; or alternatively, the first and second heat exchangers may be,

The heating conditions being turned on further comprise at least one of:

the preset heating starting timing time is met; and/or the number of the groups of groups,

when the vehicle is in a stopped state; and/or the number of the groups of groups,

and receiving a heating starting instruction sent by a user.

Optionally, the first heating current is an alternating current, the specified frequency threshold is 50 hz, and the first frequency is a fixed frequency or a periodically varying frequency.

The display device 603 in fig. 6 described above includes a screen, which may include a Liquid Crystal Display (LCD) and a Touch Panel (TP). If the screen includes a touch panel, the screen may be implemented as a touch screen to receive input signals from a user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensor may sense not only the boundary of a touch or slide action, but also the duration and pressure associated with the touch or slide operation.

The audio component 604 of fig. 6 above may be configured to output and/or input audio signals. For example, the audio component includes a Microphone (MIC) configured to receive external audio signals when the device in which the audio component is located is in an operational mode, such as a call mode, a recording mode, and a speech recognition mode. The received audio signal may be further stored in a memory or transmitted via a communication component. In some embodiments, the audio assembly further comprises a speaker for outputting audio signals.

Further, as shown in fig. 6, the vehicle apparatus further includes: communication component 605, power supply component 606, and the like. Only part of the components are schematically shown in fig. 6, which does not mean that the vehicle device only comprises the components shown in fig. 3.

The communication component 605 of fig. 6 described above is configured to facilitate wired or wireless communication between the device in which the communication component is located and other devices. The device in which the communication component is located may access a wireless network based on a communication standard, such as WiFi,2G, 3G, 4G, or 5G, or a combination thereof. In one exemplary embodiment, the communication component may be implemented based on near field communication (Near Field Communication, NFC) technology, radio frequency identification (Radio Frequency Identification, RFID) technology, infrared data association (Infrared Data Association, irDA) technology, ultra Wideband (UWB) technology, bluetooth technology, and other technologies.

Wherein the power supply assembly 606 provides power to the various components of the device in which the power supply assembly resides. The power components may include a power management system, one or more power sources, and other components associated with generating, managing, and distributing power for the devices in which the power components are located.

Accordingly, embodiments of the present application also provide a computer readable storage medium, which when executed is capable of implementing the steps in the method embodiment of fig. 4.

A first connection switch is connected in series in a circuit where a bus capacitor of a motor driving circuit is located. By controlling the first connection switch, switching between the heating circuit and the driving circuit is achieved, i.e. no bus capacitor is included in the heating circuit. When the temperature of the battery is lower than a first temperature threshold value, the battery is required to be heated, a heating circuit for heating the power battery is firstly established, and a bus capacitor is not included in the heating circuit, so that the electric energy consumption caused by the fact that a heated first heating current flows through the bus capacitor can be effectively avoided, and the heating efficiency and the electric energy effective utilization rate are improved. In addition, the position relationship between the current person and the vehicle needs to be comprehensively judged. Specifically, due to the characteristic of high alternating current impedance of the internal resistance of the power battery, when a person is not in the cabin of the vehicle, the low-frequency heating current can be utilized to heat the power battery, and higher heating efficiency and electric energy heating utilization rate can be obtained. When personnel are in the cabin of vehicle, consider the user's in the power battery heating process use experience, because low frequency heating current can lead to the motor to produce the noise when flowing through the motor, influence user's experience in the cabin, consequently, can adopt the higher heating current of than low frequency heating current frequency, when satisfying the power battery heating demand, ensure that the heating in-process can not produce bad experience to personnel in the cabin.

In the embodiment of the application, the first connecting switch connected in series with the bus capacitor is added in the direct current bus of the inverter. When the battery is not required to be heated, the motor can be driven by the power battery to rotate, the first connecting switch can be controlled to be closed, and a driving circuit is formed by the power battery, the bus capacitor, the first connecting switch, the inverter and the motor. When the power battery needs to be heated, the first connecting switch is controlled to be opened, so that a heating circuit formed by the power battery, the inverter and the motor is generated. After the heating circuit for heating the power battery is established, the heating circuit does not contain a bus capacitor, so that the electric energy consumption caused by the fact that heating current flows through the bus capacitor can be effectively avoided, and the heating efficiency and the electric energy effective utilization rate are improved. In addition, the heating circuit flowing through the heating circuit is controlled to be low-frequency current, and the internal resistance of the battery has the characteristic of large alternating current impedance to the low-frequency current under the low-temperature condition, so that the heating speed of the battery by using the low-frequency current is higher than the high-frequency heating speed, which means that the heating efficiency by using the low-frequency current is higher. And because the current flowing through the motor is low-frequency current, the consumption electric energy of the motor is lower than that of the high-frequency current, and the electric energy utilization rate is improved.

In addition, based on the first heating circuit, the position relation between the current person and the vehicle can be comprehensively judged. Specifically, due to the characteristic of high alternating current impedance of the internal resistance of the power battery, when a person is not in the cabin of the vehicle, the low-frequency current can be utilized to heat the power battery, and higher heating efficiency and electric energy heating utilization rate can be obtained. When personnel are in the cabin of vehicle, consider the user's in the power battery heating process use experience, because low frequency heating current can lead to the motor to produce the noise when flowing through the motor, influence user's experience in the cabin, consequently, can adopt the higher heating current of than low frequency heating current frequency, when satisfying the power battery heating demand, ensure that the heating in-process can not produce bad experience to personnel in the cabin.

It should be appreciated by those skilled in the art that embodiments of the invention may be provided as a method, system, or computer readable storage medium. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the invention may take the form of a computer-readable storage medium embodied in one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory. The memory may include volatile memory in a computer-readable medium, random Access Memory (RAM) and/or nonvolatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of computer-readable media.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. which are within the spirit and principles of the present application are intended to be included within the scope of the claims of the present application.

Claims

1. A battery heating method, wherein the battery heating method is applied to a controller of a battery heating system, and the battery heating system comprises: the controller is respectively in communication connection with the power battery, the first connecting switch, the inverter and the motor; the first end of the power battery is respectively connected with the first end of the bus capacitor and the first end of the inverter, the second end of the power battery is respectively connected with the second end of the first connecting switch and the second end of the inverter, the first end of the first connecting switch is connected with the second end of the bus capacitor and the first end of the second connecting switch, and the second end of the second connecting switch is connected with the motor;

The method comprises the following steps:

2. The method of claim 1, wherein the controlling the inverter to generate a second heating current for heating the power battery comprises:

3. The method of claim 2, wherein controlling the opening of the first switching device group and the closing of at least one switching device in the second switching device group in the inverter comprises:

and if the first switching device group in the inverter is controlled to be opened, and the three switching devices in the second switching device group are controlled to be closed, the power battery is connected with the three switching devices, the three windings in the motor and the bus capacitor, so that the second heating current is generated by three-phase direct current flowing through the three switching devices and the three windings.

4. The method as recited in claim 2, further comprising:

and controlling the second switching device group to be opened and controlling at least one switching device in the first switching device group to be closed, and generating a discharging circuit comprising the inverter, the motor and the bus capacitor so as to release electric energy in the bus capacitor in a discharging period.

5. The method of claim 4, wherein the heating period is greater than the discharge period.

6. The method of claim 1, wherein the controlling the inverter to generate a first heating current for heating the power battery comprises:

7. The method as recited in claim 1, further comprising:

if the heating termination condition is met, controlling the inverter to terminate generating the first heating current, and controlling the first connecting switch to be closed; wherein the heating termination condition includes at least:

8. The method of claim 7, wherein said controlling the opening of the first connection switch comprises:

9. The method of claim 7, wherein the terminating heating condition further comprises at least one of:

and receiving a heating termination instruction sent by a user.

10. The method of claim 9, wherein after controlling the inverter to terminate generating the first heating current and controlling the first connection switch to close, if the temperature of the power battery is less than a second temperature threshold, the method further comprises:

11. The method of claim 1, wherein turning on heating conditions further comprises at least one of:

and receiving a heating starting instruction sent by a user.

12. The method of claim 6, wherein the first heating current is an alternating current, the specified frequency threshold is 50 hertz, and the alternating current is a fixed frequency or a periodically varying frequency.

13. A battery heating system, the system comprising:

14. A vehicle, characterized by comprising: a vehicle body and a steer-by-wire system;

the vehicle body is provided with a memory and a processor;

the memory is used for storing one or more computer instructions;

the processor is configured to execute the one or more computer instructions for performing the steps in the method of any of claims 1 to 12.

15. A computer readable storage medium, characterized in that the computer readable storage medium, when executed, is capable of implementing the steps in the method according to any of claims 1 to 12.