An abnormal impact simulator for electric vehicle power system and a control method thereof

Abstract

The present invention relates to an abnormal impact simulator of an electric vehicle power system and a control method thereof, and belongs to the field of detection technology. The simulator includes a charging switch S1, a large-capacity capacitor group, a voltage sensor TV1, a current follower circuit (IGBT-1, IGBT-2, inductor L1), a discharge switch S2, a diode, a current sensor TA1, a controller and a host computer, etc. First, the host computer is used to set the abnormal current waveform, and the host computer sends the parameters to the controller, S1 is closed, and the controller controls the capacitor charging circuit to charge the large-capacity capacitor to a certain voltage value according to the feedback signal of TV1, S1 is disconnected, S2 is closed, and the controller controls the switches of IGBT-1 and IGBT-2 according to the feedback signals of TV1 and TA1 to generate a set current waveform. The present invention can simulate the impact of large energy, has the characteristics of flexibility and versatility, and can reduce the test time and cost of the electric vehicle power system.

Description

Technical Field

[0001] The invention belongs to the field of detection technology and relates to an abnormal impact simulator for an electric vehicle power system and a control method thereof. Background Art

[0002] At present, the power supply system of electric vehicles includes lithium battery systems or fuel cell systems, etc. Electric vehicle electrical equipment may experience short circuits, failures or overloads, etc. Instantaneous large currents will cause impacts or interference to the power supply system, and then there is a risk of damage to the power battery system or other electrical equipment. Therefore, it is necessary to develop a semi-physical simulator for abnormal impacts of the electric vehicle power supply system to simulate instantaneous large current impacts and test the stability of the electric vehicle power supply system.

[0003] There are three types of devices for simulating abnormal current in electric vehicle power systems in the prior art.

[0004] One device is a small programmable power supply. It can simulate nonlinear surge current, but the energy generated is limited, far from the requirement of more than 1000A, and the waveform is relatively basic. It is generally used for ordinary surge simulation of low-voltage circuits;

[0005] Another device is a programmable power supply used for electromagnetic compatibility testing. It can achieve short-term (within 1s) complex nonlinear current waveforms with high accuracy, but the energy generated is also limited, far from meeting the requirements of more than 1000A. It is generally used for high-frequency electromagnetic compatibility testing of power supply systems;

[0006] Another type of equipment is a large programmable power supply. The equipment is large in size and expensive. The energy generated can meet the requirements, but the waveform is relatively simple and basic and the tracking accuracy is not high. It cannot accurately generate short-term (within 1s) nonlinear impulse current waveforms. In addition, the equipment is large and not portable, and cannot be brought to the test site of the electric vehicle power system.

[0007] In summary, the existing technology cannot have the characteristics of low cost, portability, flexibility and multi-function at the same time, and cannot meet the test requirements of electric vehicle power system. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide an electric vehicle power system abnormal impact semi-physical simulator, which, as a test tool for the electric vehicle power system, can simulate large energy impacts, has the characteristics of flexibility and versatility, and can reduce the test time and cost of the electric vehicle power system.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] An abnormal impact simulator for an electric vehicle power system comprises: a charging switch S1, a diode VD1, a large-capacity capacitor group, a voltage sensor TV1, a current follower circuit (including IGBT-1, IGBT-2 and a DC filter inductor L1), a discharge switch S2, a diode VD2, a current sensor TA1, a controller and a host computer, etc.; capacitors C1 to Cn in the large-capacity capacitor group are connected in parallel.

[0011] The charging switch S1 is connected in series with the diode VD1, the voltage sensor TV1, the discharging switch S2, the collector and emitter of the IGBT-1, the DC filter inductor L1, the current sensor TA1 and the diode VD2 in sequence; one end of the large-capacity capacitor group (C1~Cn) is connected to the connection between the diode VD1 and the voltage sensor TV1, and the other end is connected to the emitter of the IGBT-2; the collector of the IGBT-2 is connected to the emitter of the IGBT-1; the controller is respectively connected to the charging switch S1, the voltage sensor TV1, the discharging switch S2, the IGBT-1, the IGBT-2, the current sensor TA1 and the host computer.

[0012] Furthermore, the control method of the simulator specifically comprises the following steps:

[0013] Step 1: The host computer sets the abnormal current waveform and sends the current waveform data to the controller.

[0014] The waveform is set to be short in time, high in energy, and nonlinear.

[0015] Step 2: The charging switch S1 is closed, and the controller controls the capacitor charging circuit to charge the large-capacity capacitor bank to a certain voltage value according to the feedback signal of the voltage sensor TV1;

[0016] Step 3: The charging switch S1 is disconnected and the discharging switch S2 is closed. The controller controls the switches of IGBT-1 and IGBT-2 according to the feedback signals of the voltage sensor TV1 and the current sensor TA1 to generate the set current waveform, apply abnormal impact to the electric vehicle power system, and finally realize the simulation of abnormal impact.

[0017] Further, in step S2, the capacitor charging circuit is controlled to charge the large-capacity capacitor bank to a certain voltage value U 0 , the expression is:

[0018]

[0019] Among them, U 0 represents the voltage value to which the large-capacity capacitor bank should be charged, Q represents the energy of the large-capacity capacitor bank, C represents the capacity of the large-capacity capacitor bank, t represents the duration of the abnormal current waveform, i(t) represents the target current value at different times t, and U dIndicates the DC bus voltage of the electric vehicle power system.

[0020] Further, in step S3, a set current waveform is generated, specifically including: IGBT-1 is closed and IGBT-2 is disconnected, resulting in an increase in current; IGBT-1 is disconnected and IGBT-2 is closed, resulting in a decrease in current; a high-frequency PWM drive signal is applied to IGBT-1 and IGBT-2, and the switches are switched quickly within a very small time interval (such as about 20,000 times per second) to increase or decrease the current; this current waveform has a sawtooth ripple, and in order to reduce the ripple, a DC filter inductor L1 is set at the output end.

[0021] In addition, in order to ensure that the main circuit will not be short-circuited, a dead zone is set, that is, the time interval during which both IGBT-1 and IGBT-2 are disconnected.

[0022] Furthermore, in step S3, unlike an ordinary PWM current follower, as the energy is released, the capacitor voltage is continuously decreasing, and the PWM drive signal is adjusted and changed according to the feedback signals of the voltage sensor TV1 and the current sensor TA1, so as to ensure that the current tracks a given current waveform.

[0023] Furthermore, the voltage signal of the capacitor in the large-capacity capacitor group is detected by using the voltage sensor TV1, and the actual output current signal is detected by using the current sensor TA1.

[0024] Furthermore, the current signal is collected by the current sensor TA1, and the controller collects and transmits it to the host computer and displays it to the test personnel, who can query the actual current waveform.

[0025] The beneficial effects of the present invention are as follows: the present invention uses a large-capacity capacitor group, an IGBT current tracking current and an automatic controller, which can realize a variety of nonlinear current curves with relatively high power in a very short time. Since the test time is short, the volume of the components in the equipment is not large and the cost is not high, the entire equipment has the characteristics of low cost, portability, flexibility and multi-function, which is superior to the existing technology.

[0026] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0028] Figure 1A structural diagram of the semi-physical simulator for abnormal impact of an electric vehicle power system provided by the present invention;

[0029] Figure 2 A flow chart of a control method of a semi-physical simulator for abnormal impact of an electric vehicle power system provided by the present invention;

[0030] Figure 3 This is the abnormal current wave waveform diagram edited by the tester on the host computer;

[0031] Figure 4 This is a schematic diagram of PWM drive signal.

[0032] Reference numerals: S1 - charging switch; S2 - discharging switch; C1 - Cn - large-capacitance capacitor group; TV1 - voltage sensor; TA1 - current sensor; L1 - DC filter inductor. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0035] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] See also Figure 1 to Figure 4 , Figure 1The figure shows a structural diagram of a semi-physical simulator for abnormal impact of an electric vehicle power system, which includes: a charging switch S1, a diode VD1, a large-capacity capacitor group (C1-Cn), a voltage sensor TV1, a current follower circuit (including IGBT-1, IGBT-2, and a DC filter inductor L1), a discharge switch S2, a diode VD2, a current sensor TA1, a controller, and a host computer. Among them, the charging switch S1 is connected in series with the diode VD1, the voltage sensor TV1, the discharge switch S2, the collector and emitter of the IGBT-1, the DC filter inductor L1, the current sensor TA1, and the diode VD2; one end of the large-capacity capacitor group (C1-Cn) is connected to the connection between the diode VD1 and the voltage sensor TV1, and the other end is connected to the emitter of the IGBT-2; the collector of the IGBT-2 is connected to the emitter of the IGBT-1; the controller is connected to the charging switch S1, the voltage sensor TV1, the discharge switch S2, the IGBT-1, the IGBT-2, the current sensor TA1, and the host computer respectively.

[0037] Figure 2 The control method of the semi-physical simulator is shown, which specifically includes the following steps:

[0038] Step 1: The tester edits the abnormal current waveform data on the host computer, confirms that the waveform meets the requirements through the display, and then sends the current waveform data i(t) to the controller. The current waveform data i(t) is as follows: Figure 3 shown.

[0039] The device's capacity is 50F. According to the following formula, the system calculates the charging voltage value U 0 The system capacitor charging voltage target value of 700 V is also sent to the controller.

[0040]

[0041] Among them, U 0 represents the voltage value to which the large-capacity capacitor bank should be charged, Q represents the energy of the large-capacity capacitor bank, C represents the capacity of the large-capacity capacitor bank, t represents the duration of the abnormal current waveform, i(t) represents the target current value at different times t, and U d Indicates the DC bus voltage of the electric vehicle power system.

[0042] Step 2: Connect the 800V DC power supply in the test room to the semi-physical simulator, close the charging switch S1, and the voltage on the capacitor gradually increases. According to the feedback signal of the voltage sensor TV1, the controller disconnects the charging switch S1 when the voltage reaches 700V, and the capacitor voltage stabilizes at 700V. Disconnect the semi-physical simulator from the 800V DC power supply. Bring the semi-physical simulator to the test site of the electric vehicle power system.

[0043] Step 3: The charging switch is opened and the discharging switch is closed.

[0044] Step 4: The discharge switch S2 is closed, and the controller controls the switches of IGBT-1 and IGBT-2 according to the feedback signal of the current sensor TA1 and the capacitor voltage signal collected by the voltage sensor TV1 to generate a set current sawtooth waveform.

[0045] When the semi-physical simulator is working, IGBT-1 is closed and IGBT-2 is disconnected, resulting in an increase in current; IGBT-1 is disconnected and IGBT-2 is closed, resulting in a decrease in current. A 50kHZ PWM drive signal is applied to IGBT-1 and IGBT-2. Rapid switching within a time interval of 0.02ms is used to increase and decrease the current. This current waveform has a sawtooth ripple. The working principle is as follows Figure 4 shown.

[0046] To reduce the ripple, a DC filter inductor L1 is set at the output end, and the inductance value is set to 2mH. The current waveform becomes smoother through the inductor L1, meeting the test requirements.

[0047] The current signal is collected by the current sensor TA1, and the controller collects and transmits it to the host computer and displays it to the test personnel. The test personnel can query the actual current waveform and observe the effect of the application of the impulse current.

[0048] Finally, by observing and recording the response of the electric vehicle power system, the impact resistance of the power system was examined using a semi-physical simulation test method.

[0049] The simulator of the present invention is low-cost, portable, flexible and multifunctional, and can well realize short-term impact current with nonlinear complex waveform. The present invention is practical, convenient and efficient, and can be widely used in the test of impact resistance and reliability of electric vehicle power supply system. The impact current waveform required for the test is easy to produce and can be realized quickly. It is flexible and efficient, so that the test requirements of electric vehicle power supply system can be quickly met. The shortcomings and deficiencies of the prior art are overcome.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. An abnormal impact simulator for an electric vehicle power system, characterized in that: The simulator includes: a charging switch S1, a large-capacity capacitor group, a voltage sensor TV1, a current follower circuit, a discharge switch S2, diodes VD1-VD2, a current sensor TA1, a controller and a host computer; the capacitors C1-Cn in the large-capacity capacitor group are connected in parallel; the current follower circuit includes IGBT-1, IGBT-2 and a DC filter inductor L1; The charging switch S1 is connected in series with the diode VD1, the voltage sensor TV1, the discharging switch S2, the collector and emitter of IGBT-1, the DC filter inductor L1, the current sensor TA1 and the diode VD2 in sequence; one end of the large-capacity capacitor group (C1~Cn) is connected to the connection between the diode VD1 and the voltage sensor TV1, and the other end is connected to the emitter of IGBT-2; the collector of IGBT-2 is connected to the emitter of IGBT-1; the controller is respectively connected to the charging switch S1, the voltage sensor TV1, the discharging switch S2, the base of IGBT-1, the base of IGBT-2, the current sensor TA1 and the host computer.

2. The abnormal impact simulator of the electric vehicle power system according to claim 1 is characterized in that: The control method of the simulator specifically comprises the following steps: Step 1: The host computer sets the abnormal current waveform and sends the current waveform data to the controller; Step 2: The charging switch S1 is closed, and the controller controls the capacitor charging circuit to charge the large-capacity capacitor bank to a certain voltage value according to the feedback signal of the voltage sensor TV1; Step 3: The charging switch S1 is turned off, and the discharging switch S2 is turned on. The controller controls the switches of IGBT-1 and IGBT-2 according to the feedback signals of the voltage sensor TV1 and the current sensor TA1, generates a set current waveform, applies an abnormal impact to the electric vehicle power system, and finally realizes the simulation of the abnormal impact. Generate a set current waveform, specifically including: IGBT-1 is closed and IGBT-2 is disconnected, resulting in an increase in current; IGBT-1 is disconnected and IGBT-2 is closed, resulting in a decrease in current; a high-frequency PWM drive signal is applied to IGBT-1 and IGBT-2, and the switch is quickly switched within a very small time interval to increase or decrease the current; in addition, in order to ensure that the main circuit will not be short-circuited, a dead zone is set, that is, the time interval when both IGBT-1 and IGBT-2 are disconnected.

3. The abnormal impact simulator of the electric vehicle power system according to claim 2 is characterized in that: In step S2, the capacitor charging circuit is controlled to charge the large-capacity capacitor bank to a certain voltage value U0, which is expressed as: Among them, U0 represents the voltage value that the large-capacity capacitor bank should be charged to, Q represents the energy of the large-capacity capacitor bank, C represents the capacity of the large-capacity capacitor bank, t represents the duration of the abnormal current waveform, i(t) represents the target current value at different times t, and U d Indicates the DC bus voltage of the electric vehicle power system.

4. The abnormal impact simulator of the electric vehicle power system according to claim 3 is characterized in that: In step S3, the PWM driving signal is adjusted and changed according to the feedback signals of the voltage sensor TV1 and the current sensor TA1, so as to ensure that the current tracks a given current waveform.

Images