Power battery low-temperature heating device and heating method

Abstract

The invention discloses a power battery low-temperature heating device and method, and belongs to the technical field of power battery low-temperature heating. The device comprises a controller, a power supply assembly, a switch assembly and a heating ring; the power supply assembly, the switch assembly and the heating ring are connected in series; the heating ring correspondingly surrounds the power battery; the power supply assembly is used for providing alternating current for the heating ring; the controller is electrically connected with the switch assembly and used for controlling the switch assembly to be switched on and switched off. When the switch assembly is closed, an access is formed between the heating ring and the power supply assembly, the heating ring converts high-frequency alternating current into a high-frequency alternating magnetic field, and the high-frequency alternating magnetic field excites and vibrates free charges in the power battery, so that the power battery is heated. According to the invention, high-frequency alternating current can be converted into a high-frequency alternating magnetic field, and free charges in the power battery are excited and vibrated, so that the power battery generates heat, and rapid temperature rise of the power battery is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature heating of power batteries, and in particular relates to a low-temperature heating device and a heating method for a power battery. Background Art

[0002] Currently, there are three main ways to preheat power batteries, namely, liquid heating, PTC heating, and heating by setting a heating resistor inside the battery. All three heating methods have corresponding problems.

[0003] Liquid heating is a traditional heating technology. Liquid heating will not only significantly reduce the energy density of the power battery, but also has problems such as low heating efficiency and slow heating rate.

[0004] PTC heating is the main technology for preheating existing power batteries, but PTC heating has disadvantages such as low heating efficiency, poor uniformity, high safety hazards, poor control accuracy, and slow heating rate.

[0005] Setting a heating resistor inside the battery is a new technology in recent years. Although this heating method improves the target heating rate, it also has problems such as high management and control costs and overly complex control. Currently, existing methods cannot effectively solve the battery preheating problem in a short period of time. Summary of the invention

[0006] In view of this, the present invention provides a low-temperature heating device and a heating method for a power battery, which can convert high-frequency alternating current into a high-frequency alternating magnetic field, excite and vibrate the free charges inside the power battery, thereby causing the power battery to generate heat and achieve rapid heating of the power battery.

[0007] The present invention is achieved through the following technical solutions:

[0008] A low-temperature heating device for a power battery, comprising a controller, a power supply component, a switch component, and a heating coil;

[0009] The power supply assembly, the switch assembly and the heating coil are connected in series, and the heating coil is correspondingly arranged around the outside of the power battery; the power supply assembly is used to provide alternating current to the heating coil;

[0010] The controller is electrically connected to the switch assembly and is used to control the opening and closing of the switch assembly;

[0011] When the switch assembly is closed, a path is formed between the heating coil and the power supply assembly, and the heating coil converts high-frequency alternating current into a high-frequency alternating magnetic field. The high-frequency alternating magnetic field excites and vibrates the free charges in the power battery, thereby heating the power battery.

[0012] Furthermore, the power supply component includes a power supply and an inverter. The power supply outputs direct current, and the inverter is used to convert direct current into high-frequency alternating current. The inverter is electrically connected to the controller, and the controller can control the frequency of the alternating current by controlling the inverter.

[0013] Furthermore, the controller is also electrically connected to the power battery, and the power battery can transmit temperature data to the controller. The controller can control the frequency of the alternating current output by the inverter according to the received temperature data and the set target temperature and target heating rate, so as to heat the power battery to the target temperature.

[0014] Furthermore, the power battery is a single power battery, the switch assembly is a relay, and the relay is arranged between the power supply and the inverter;

[0015] The relay is electrically connected to the controller, and the controller can control the opening and closing of the relay.

[0016] Furthermore, the power battery includes a plurality of battery modules connected in parallel, the switch assembly includes a relay and a plurality of selection switches Q1, Q2, Q3, Q4...Qn, where n is a positive integer; the selection switches correspond to the battery modules one by one; each selection switch is respectively connected in series with a heating coil outside a corresponding battery module;

[0017] The relay and the plurality of selection switches are electrically connected to the controller respectively, and the controller can control the opening and closing of the relay and the plurality of selection switches respectively.

[0018] Furthermore, the power battery includes a plurality of battery modules connected in parallel, the switch assembly includes a relay and a plurality of selection switches Q1, Q2, Q3, Q4...Qn, where n is a positive integer; the selection switches correspond to the battery modules one by one; each selection switch is respectively connected in series with a heating coil outside a corresponding battery module;

[0019] The relay and the plurality of selection switches are electrically connected to the controller respectively, and the controller can control the opening and closing of the relay and the plurality of selection switches respectively.

[0020] A power battery low temperature heating method, based on a power battery low temperature heating device, comprises the following steps:

[0021] Step 1: Turn on the controller;

[0022] Step 2: Close the relay and the selection switch corresponding to the battery module to be heated through the controller;

[0023] Step 3, setting the target temperature and target heating rate in the controller;

[0024] Step 4: Turn on the inverter through the controller. At this time, the frequency of the high-frequency alternating current output by the inverter is frequency I;

[0025] Step 5: The controller calculates the frequency II of the high-frequency alternating current that the inverter should output according to the target heating rate, and compares the frequency I with the frequency II;

[0026] If frequency I = frequency II, heating continues. During the heating process, the controller collects the temperature data of each battery module in real time. When the temperature data of the battery module reaches the set target temperature, the controller controls the corresponding selection switch to disconnect;

[0027] If frequency I ≠ frequency II, the controller controls the inverter to adjust the frequency of the high-frequency alternating current, thereby adjusting the frequency of the high-frequency alternating current to frequency II; after adjustment, heating continues. During the heating process, the controller collects the temperature data of each battery module in real time. When the temperature data of the battery module reaches the set target temperature, the controller controls the corresponding selection switch to disconnect.

[0028] Furthermore, the controller calculates the frequency IIf of the high-frequency alternating current that the inverter should output according to the target heating rate. Ⅱ The calculation method is:

[0029] Step 51: Calculate the effective power P required for heating according to the target heating rate. useful , the calculation formula is as follows:

[0030] P useful =m·c·V

[0031] Where: m is the mass of the power battery to be heated; c is the specific heat capacity of the power battery material; V is the target heating rate;

[0032] Step 52: According to the effective power P useful Calculate the total power P that the power battery needs to input input , the calculation formula is as follows:

[0033]

[0034] Where: η total is the total efficiency of the system, including the effects of electromagnetic coupling, eddy current loss, heat dissipation loss and parasitic loss;

[0035] Step 53: According to the total input power P input Calculate the amplitude I of the induced current generated by the alternating magnetic field 感 :The calculation method is as follows:

[0036] According to the principle of induction heating, the input power P input It can be considered as equal to the induced current generated by the alternating magnetic field to generate Joule heat; that is, the input power P input is equal to the induced power P; then the amplitude of the induced current I 感 for:

[0037]

[0038] Where R is the resistance of the inductive conductor in the power battery;

[0039] Step 54: According to the amplitude of the induced current I 感 Calculate the frequency IIf of the high-frequency alternating current that should be output Ⅱ :

[0040]

[0041] Among them, r is the radius of the space enclosed by the heating coil, N is the number of turns of the heating coil, and A is the magnetic area of ​​the induction conductor in the power battery: μ 0 is the vacuum permeability, which is 4π×10 -7 H / m; I 0 is the amplitude of the high-frequency alternating current.

[0042] Beneficial effects:

[0043] (1) The present invention provides a low-temperature heating device for a power battery, which uses a heating coil to convert a high-frequency alternating current into a high-frequency alternating magnetic field to act on the free charges of the power battery, thereby heating the power battery, thereby achieving rapid heating of the battery, and has a simple structure, low cost and good effect.

[0044] (2) The power supply assembly provided by the present invention includes an inverter, which is electrically connected to a controller. The controller can control the duty cycle and frequency of the alternating current by controlling the inverter, and can flexibly change the heating power of the power battery according to demand.

[0045] (3) The controller of the present invention can receive the temperature data of the power battery. The controller can control the duty cycle and frequency of the alternating current output by the inverter according to the received temperature data and the set target temperature and target heating rate, so as to achieve the optimal heating current frequency and heating power of the power battery.

[0046] (4) Each battery module of the present invention is provided with a corresponding selection switch, so as to achieve targeted heating of the battery module.

[0047] (5) The present invention provides a method for low-temperature heating of a power battery, which can calculate the frequency II of the high-frequency alternating current that the inverter should output according to the target heating rate, and adjust the frequency I of the high-frequency alternating current output by the inverter to frequency II, thereby heating the power battery, achieving rapid and accurate heating of the battery with good heating effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic diagram of a low-temperature heating device for a power battery according to the present invention;

[0049] Figure 2 This is a flow chart of the low-temperature heating method for a power battery of the present invention;

[0050] Among them, 10 is a controller, 11 is a power supply, 12 is a relay, 13 is an inverter, 14 is a battery module, and 15 is a heating coil. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0052] Embodiment 1:

[0053] This embodiment provides a low-temperature heating device for a power battery, which is used to heat the power battery. Figure 1 , including a controller 10, a power supply component, a switch component, and a heating coil 15;

[0054] The power supply assembly, the switch assembly and the heating coil 15 are connected in series, and the heating coil 15 is correspondingly arranged around the outside of the power battery; the power supply assembly is used to provide alternating current to the heating coil 15;

[0055] The controller 10 is electrically connected to the switch assembly and is used to control the opening and closing of the switch assembly;

[0056] When the switch assembly is closed, a passage is formed between the heating coil 15 and the power supply assembly, and the heating coil 15 converts high-frequency alternating current into a high-frequency alternating magnetic field. The high-frequency alternating magnetic field excites and vibrates the free charges in the power battery, thereby heating the power battery.

[0057] The present embodiment provides a low-temperature heating device for a power battery, which uses a heating coil 15 to convert a high-frequency alternating current into a high-frequency alternating magnetic field to act on the free charges of the power battery, thereby heating the power battery, thereby achieving rapid heating of the battery, and has a simple structure, low cost and good effect.

[0058] The power supply assembly includes a power supply 11 and an inverter 13. The power supply 11 outputs direct current, and the inverter 13 is used to convert the direct current into high-frequency alternating current. The inverter 13 is electrically connected to the controller 10, and the controller 10 can control the duty cycle and frequency of the alternating current by controlling the inverter 13.

[0059] The controller 10 is also electrically connected to the power battery, and the power battery can transmit temperature data to the controller 10. The controller 10 can control the duty cycle and frequency of the alternating current output by the inverter 13 according to the received temperature data and the set target temperature and target heating rate, and heat the power battery to the target temperature, thereby achieving the optimal heating current frequency and heating power of the power battery.

[0060] The controller 10 may also collect voltage data, current data, and state of charge (SOC) data of the battery.

[0061] The heating coil 15 is a coil wound with Litz wire or a wound copper tube.

[0062] In one embodiment, the power battery is a single power battery, the switch component is a relay 12, and the relay 12 is arranged between the power source 11 and the inverter 13. The relay 12 is electrically connected to the controller 10, and the controller 10 can control the opening and closing of the relay 12;

[0063] In another embodiment, the power battery includes a number of battery modules connected in parallel, and the switch assembly includes a relay 12 and a number of selection switches Q1, Q2, Q3, Q4...Qn, where n is a positive integer; the selection switches correspond to the battery modules one by one; each selection switch is respectively connected in series with the heating coil 15 outside the corresponding battery module; the selection switch is used to control whether the heating coil 15 on the corresponding branch generates a magnetic field; the relay 12 and the number of selection switches are respectively electrically connected to the controller 10, and the controller 10 can respectively control the opening and closing of the relay 12 and the number of selection switches, thereby realizing targeted heating of the battery module.

[0064] Embodiment 2:

[0065] This embodiment provides a low temperature heating method for a power battery based on Embodiment 1. Figure 2 ,

[0066] Step 1: Turn on the controller 10;

[0067] Step 2: closing the relay 12 and the selection switch corresponding to the battery module to be heated through the controller 10;

[0068] Step 3: setting the target temperature and the target heating rate in the controller 10;

[0069] Step 4: Turn on the inverter 13 through the controller 10. At this time, the frequency of the high-frequency alternating current output by the inverter 13 is frequency I;

[0070] Step 5, the controller 10 calculates the frequency II of the high-frequency alternating current that the inverter 13 should output according to the target heating rate, and compares the frequency I with the frequency II;

[0071] If frequency I = frequency II, heating continues. During the heating process, the controller 10 collects temperature data of each battery module in real time. When the temperature data of the battery module reaches the set target temperature, the controller controls the corresponding selection switch to be disconnected.

[0072] If frequency I ≠ frequency II, the controller 10 controls the inverter 13 to adjust the duty cycle and frequency of the high-frequency alternating current, thereby adjusting the frequency of the high-frequency alternating current to frequency II. After the adjustment, heating continues. During the heating process, the controller 10 collects the temperature data of each battery module in real time. When the temperature data of the battery module reaches the set target temperature, the controller controls the corresponding selection switch to be disconnected;

[0073] The controller 10 calculates the frequency IIf of the high-frequency alternating current that the inverter 13 should output according to the target heating rate. Ⅱ The calculation method is:

[0074] Step 51: Calculate the effective power P required for heating according to the target heating rate. useful (Unit: W), the calculation formula is as follows:

[0075] P useful =m·c·V (1)

[0076] Wherein: m is the mass of the power battery to be heated (unit: kg); c is the specific heat capacity of the power battery material (unit: J / (kg·K)); V is the target heating rate (unit: K / s);

[0077] Step 52: Due to various losses in the system, the total power P that the power battery needs to input input will be greater than the effective power P useful According to the effective power P useful Calculate the total power P that the power battery needs to input input , the calculation formula is as follows:

[0078]

[0079] Where: η total is the total efficiency of the system, including the effects of electromagnetic coupling, eddy current loss, heat dissipation loss and parasitic loss;

[0080] Step 53: According to the total input power P input Calculate the amplitude I of the induced current generated by the alternating magnetic field 感 (Unit: A): The calculation method is as follows:

[0081] According to the principle of induction heating, the input power P input It can be considered as equal to the induced current generated by the alternating magnetic field to generate Joule heat. That is, the input power P input is equal to the induced power P; then the amplitude of the induced current I 感 for:

[0082]

[0083] Where R is the resistance of the inductive conductor in the power battery (unit: Ω);

[0084] Step 54: According to the amplitude of the induced current I 感 Calculate the frequency IIf of the high-frequency alternating current that should be output Ⅱ (Unit: Hz):

[0085]

[0086] Among them, r is the radius of the space enclosed by the heating coil (unit: m), N is the number of turns of the heating coil, and A is the magnetic area of ​​the induction conductor in the power battery (unit: m 2 ): μ 0 is the vacuum permeability, which is 4π×10 -7 H / m; I 0 It is the amplitude of high-frequency alternating current (unit: A).

[0087] Furthermore, the derivation process of formula (4) is as follows:

[0088] First, the amplitude of the induced current is related to the frequency and magnetic induction intensity of the electromagnetic field. According to Faraday's law of electromagnetic induction, the induced electromotive force E 感 It can be expressed as:

[0089] E 感 =N·A·2πf Ⅱ ·B 0 (5)

[0090] Among them, B 0 is the magnetic field strength at the center of the heating coil;

[0091] Then, according to Ohm's law, the induced electromotive force E 感 It can also be expressed as:

[0092] E 感 =I 感 ·R (6)

[0093] Combining formula (5) and formula (6), we have:

[0094]

[0095] Finally, according to the Biot-Savart law, the magnetic field strength B at the center of the heating coil is 0 It can be expressed as:

[0096]

[0097] Substituting formula (8) into formula (7) yields formula (4).

[0098] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-temperature heating device for a power battery, characterized in that: Including controller, power supply component, switch component, heating coil; The power supply assembly, the switch assembly and the heating coil are connected in series, and the heating coil is correspondingly arranged around the outside of the power battery; the power supply assembly is used to provide alternating current to the heating coil; The controller is electrically connected to the switch assembly and is used to control the opening and closing of the switch assembly; When the switch assembly is closed, a path is formed between the heating coil and the power supply assembly, and the heating coil converts high-frequency alternating current into a high-frequency alternating magnetic field. The high-frequency alternating magnetic field excites and vibrates the free charges in the power battery, thereby heating the power battery.

2. A power battery low temperature heating device as claimed in claim 1, characterized in that: The power supply assembly includes a power supply and an inverter. The power supply outputs direct current, and the inverter is used to convert direct current into high-frequency alternating current. The inverter is electrically connected to the controller, and the controller can control the frequency of the alternating current by controlling the inverter.

3. A power battery low temperature heating device as claimed in claim 2, characterized in that: The controller is also electrically connected to the power battery, which can transmit temperature data to the controller. The controller can control the frequency of the alternating current output by the inverter based on the received temperature data and the set target temperature and target heating rate, so as to heat the power battery to the target temperature.

4. A power battery low temperature heating device as claimed in any one of claims 1 to 3, characterized in that: The power battery is a single power battery, the switch component is a relay, and the relay is arranged between the power source and the inverter; The relay is electrically connected to the controller, and the controller can control the opening and closing of the relay.

5. A power battery low temperature heating device as claimed in any one of claims 1 to 3, characterized in that: The power battery includes a plurality of battery modules connected in parallel, and the switch assembly includes a relay and a plurality of selection switches Q1, Q2, Q3, Q4...Qn, where n is a positive integer; the selection switches correspond to the battery modules one by one; each selection switch is respectively connected in series with a heating coil outside a corresponding battery module; The relay and the plurality of selection switches are electrically connected to the controller respectively, and the controller can control the opening and closing of the relay and the plurality of selection switches respectively.

6. A power battery low temperature heating device as claimed in claim 3, characterized in that: The power battery includes a plurality of battery modules connected in parallel, and the switch assembly includes a relay and a plurality of selection switches Q1, Q2, Q3, Q4...Qn, where n is a positive integer; the selection switches correspond to the battery modules one by one; each selection switch is respectively connected in series with a heating coil outside a corresponding battery module; The relay and the plurality of selection switches are electrically connected to the controller respectively, and the controller can control the opening and closing of the relay and the plurality of selection switches respectively.

7. A power battery low temperature heating method, based on the power battery low temperature heating device according to claim 6, characterized in that: The following steps are involved: Step 1: Turn on the controller; Step 2: Close the relay and the selection switch corresponding to the battery module to be heated through the controller; Step 3, setting the target temperature and target heating rate in the controller; Step 4: Turn on the inverter through the controller. At this time, the frequency of the high-frequency alternating current output by the inverter is frequency I; Step 5: The controller calculates the frequency II of the high-frequency alternating current that the inverter should output according to the target heating rate, and compares the frequency I with the frequency II; If frequency I = frequency II, heating continues. During the heating process, the controller collects the temperature data of each battery module in real time. When the temperature data of the battery module reaches the set target temperature, the controller controls the corresponding selection switch to disconnect; If frequency I≠frequency II, the controller controls the inverter to adjust the frequency of the high-frequency alternating current, thereby adjusting the frequency of the high-frequency alternating current to frequency II; After adjustment, heating continues. During the heating process, the controller collects the temperature data of each battery module in real time. When the temperature data of the battery module reaches the set target temperature, the controller controls the corresponding selection switch to disconnect.

8. A method for low temperature heating of a power battery as claimed in claim 7, characterized in that: The controller above calculates the frequency IIf of the high-frequency alternating current that the inverter should output based on the target heating rate. Ⅱ The calculation method is: Step 51: Calculate the effective power P required for heating according to the target heating rate. useful , the calculation formula is as follows: P useful =m·c·V in; m is the mass of the power battery to be heated; c is the specific heat capacity of the power battery material; V is the target heating rate; Step 52: According to the effective power P useful Calculate the total power P that the power battery needs to input input , the calculation formula is as follows: Where: η total is the total efficiency of the system, including the effects of electromagnetic coupling, eddy current loss, heat dissipation loss and parasitic loss; Step 53: According to the total input power P input Calculate the amplitude I of the induced current generated by the alternating magnetic field 感 :The calculation method is as follows: According to the principle of induction heating, the input power P input It can be considered as equal to the induced current generated by the alternating magnetic field to generate Joule heat; that is, the input power P input is equal to the induced power P; then the amplitude of the induced current I 感 for: Where R is the resistance of the inductive conductor in the power battery; Step 54: According to the amplitude of the induced current I 感 Calculate the frequency IIf of the high-frequency alternating current that should be output Ⅱ : Among them, r is the radius of the space enclosed by the heating coil, N is the number of turns of the heating coil, A is the magnetic area of ​​the induction conductor in the power battery, and μ0 is the magnetic permeability of vacuum, which is 4π×10 -7 H / m; I0 is the amplitude of high-frequency alternating current.

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