Variable parameter differential type EPS power supply voltage validity detection method

Abstract

The application discloses a variable parameter differential EPS power supply voltage effectiveness detection method, and relates to the technical field of EPS power supply detection, and comprises an LDO chip, an MCU chip and a voltage dividing circuit, the voltage dividing circuit comprises two circuits, one of the circuits is composed of a resistor R1 and a resistor R2, and the divided voltage is U1; the other circuit is composed of a resistor R3 and a resistor R4, and the divided voltage is U2.The application realizes the effectiveness detection of the EPS power supply voltage, accurately identifies the MCU chip power supply voltage state, processes the reliable sampling signal, avoids the EPS false alarm caused by the abnormal sampling signal due to the insufficient EPS power supply voltage, and the power management function realized by the technical scheme can effectively protect the normal work of the product under different power supply voltages, improves the stability and service life of the product, optimizes the user experience, and is a low-cost solution.

Description

Technical Field

[0001] This invention relates to the field of EPS power supply testing technology, specifically to a method for detecting the effectiveness of EPS power supply voltage using a variable-parameter differential voltage method. Background Technology

[0002] A stable power supply for the MCU chip (microcontroller) of the EPS (Electronic Power Steering) system is typically provided using an LDO (Low-Voltage Linear Regulator) chip. The standard output voltage of the LDO chip is V. REG The input voltage is 3.3V or 5V, when the LDO chip's input voltage is 2.5V to V. REG At this time, the LDO chip output voltage = LDO chip input voltage - voltage drop (DropoutVoltage). The LDO chip voltage drop is positively correlated with the LDO output current (OutputCurrent). Since the MCU chip has a small operating current, the LDO chip voltage drop is negligible. Therefore, the LDO chip output voltage = LDO chip input voltage.

[0003] Minimum voltage of MCU chip V MCUmin The highest voltage of the MCU chip is V MCUmax Typically, MCU chips operate at a voltage of approximately 2.7 to 5.5V.

[0004] The reference voltage of the ADC (Analog-to-Digital Converter) integrated inside the MCU chip is actually the MCU chip's supply voltage V. MCU The ADC sampling full-scale range is 2 n Sampling accuracy is

[0005] When the EPS is working normally, it acquires various sensor signals through the integrated ADC module port, processes them through algorithms in the software, and then controls the effective output of the motor. When the MCU chip supply voltage V MCU Poor stability can cause fluctuations in the sampling accuracy of the ADC module, errors in sensor signal acquisition, and software program errors that can lead to false alarms from the EPS or malfunctions in motor control. Therefore, the sampling accuracy of the ADC module is closely related to the accuracy of motor control.

[0006] insufficient:

[0007] Since all electrical appliances in the vehicle are powered by the battery, their use may cause power interference; the charging and discharging of the vehicle's battery and the gradual rise and fall of the supply voltage will also cause changes in the supply voltage.

[0008] When the vehicle's power supply voltage changes, the following situations may occur (based on the LDO chip's standard output voltage V). REG =5V as an example):

[0009] ①5V<Power≤ Maximum operating voltage of LDO chip: LDO chip output voltage V REG =5V, ADC module sampling is normal, chip is working normally;

[0010] ②V MCUmin <Power≤5V: LDO chip output voltage = MCU chip supply voltage (V) MCU =Power, ADC module sampling accuracy change (sampling accuracy is When the external sensor samples the analog signal voltage normally, the digital value after ADC conversion is inversely proportional to the supply voltage. The sampled voltage calculated by the program through the algorithm is greater than the actual analog signal voltage, causing the program to mistakenly believe that the sensor signal is abnormal and thus issue an alarm signal. At this time, except for the MCU chip ADC module malfunction, all other components of the EPS are in normal condition, so the alarm signal is a false alarm.

[0011] ③Power < V MCUmin LDO chip output voltage = MCU chip supply voltage (V) MCU <V MCUmin The MCU chip is not working.

[0012] The single-channel voltage sampling circuit cannot perform normal detection under the conditions described in ② above, and cannot accurately realize the power management function of the EPS; therefore, we provide a variable-parameter differential EPS power supply voltage validity detection method to solve the above problems. Summary of the Invention

[0013] To address the problems existing in the prior art, this invention provides a variable-parameter differential EPS power supply voltage validity detection method, solving the problem of single-channel voltage sampling circuits in V MCUmin The problem is that the EPS cannot be detected properly when the power is less than or equal to 5V, and therefore cannot accurately perform its power management function.

[0014] To achieve the above objectives, the present invention employs a variable-parameter differential EPS power supply voltage validity detection method, comprising an LDO chip, an MCU chip, and a voltage divider circuit. The voltage divider circuit includes two paths, one of which consists of resistors R1 and R2, dividing the voltage by U1. The voltage division ratio of resistors R1 and R2 is specified. The other circuit consists of resistors R3 and R4, with a voltage division of U2. The voltage division ratio between resistors R3 and R4 is... In this voltage divider circuit, the voltage division ratio K1 ≠ K2. The upper end of the two voltage divider circuits is connected to Power, and the lower end is connected to GND. The input voltage of the LDO chip is represented by Power, and the output voltage is represented by V. MCU It means, V MCU Simultaneously supply power to the MCU chip;

[0015] The voltage divider U1 = Power·K1, the circuit voltage divider U2 = Power·K2, the MCU chip has two pins of the ADC conversion module, the two pins are AD_1 and AD_2 respectively, and the voltage dividers U1 and U2 are connected to the AD_1 and AD_2 pins of the MCU chip respectively in a differential routing manner;

[0016] The ADC sampling full scale is 2 n The digital values ​​of voltages U1 and U2 after analog-to-digital conversion are AD1 and AD2, respectively. ΔE1 and ΔE2 are common-mode interference. Since the voltage dividers U1 and U2 are implemented using differential routing, ΔE1 = ΔE2 = ΔE.

[0017] Eliminating common-mode interference using differential methods: Variable-parameter differential calculation formula:

[0018]

[0019] The value of ΔAD is calculated using the formula for calculating the difference between the upper and lower parameters. Then, the value of ΔAD and 2 are used... n The comparison of |K1-K2| determines whether the EPS power supply voltage is valid or invalid under this state, and whether the ADC sampling value is reliable or unreliable.

[0020] As a further optimization of the above scheme, when ΔAD = 2 n When |K1-K2|, the algorithm calculates Power = V. MCU V MCU ≤V REG The MCU chip's power supply voltage is in an undervoltage state. The algorithm determines that the EPS power supply voltage is invalid in this state, the ADC sampling value is unreliable, and the analog signal sampling is not processed.

[0021] As a further optimization of the above scheme, when ΔAD>2 n When |K1-K2|, the algorithm calculates that Power > V. MCU V MCU =V REG The MCU chip power supply voltage is in a normal state. The algorithm determines that the EPS power supply voltage is in a valid state under this state, the ADC sampling value is reliable, and the analog signal sampling is processed normally.

[0022] As a further optimization of the above scheme, the accurate EPS supply voltage is calculated by an algorithm under the condition that the ADC sampling value is reliable. The specific formula is as follows:

[0023]

[0024] The variable-parameter differential EPS power supply voltage effectiveness detection method of the present invention has the following beneficial effects:

[0025] The present invention discloses a variable-parameter differential EPS power supply voltage validity detection method. This invention realizes the validity detection of EPS power supply voltage, accurately identifies the power supply voltage status of MCU chip, processes reliable sampling signals, and avoids false alarms caused by abnormal sampling signals due to insufficient EPS power supply voltage. The power management function implemented by this technical solution can effectively protect the normal operation of the product under different power supply voltages, improve the stability and lifespan of the product, optimize the user experience, and is a low-cost solution.

[0026] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and that the embodiments of the present invention include many changes, modifications and equivalents within the spirit and scope of the appended claims. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the voltage divider circuit structure of the present invention;

[0028] Figure 2 This is a graph showing the input-output voltage relationship of the LDO chip of the present invention.

[0029] Figure 3 This is a graph showing the relationship between the voltage drop and output current of the LDO chip of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Please refer to the instruction manual appendix. Figure 1-3 This invention provides a technical solution: a variable-parameter differential EPS power supply voltage validity detection method. This invention mainly solves the problem of single-channel voltage sampling circuits in V... MCUminThe problem is that the EPS cannot be detected properly when the power is less than or equal to 5V, and the power management function of the EPS cannot be accurately implemented. This issue needs to be addressed to determine the validity of the EPS power supply voltage and to realize the EPS power management function.

[0033] The main idea of ​​this invention is to use two voltage divider circuits with the same source but different parameters to acquire the EPS power supply voltage, and to achieve the desired voltage level within 5V < Power ≤ LDO chip maximum operating voltage and V based on the input and output voltage characteristics of the LDO chip and software algorithms. MCUmin The validity of the EPS power supply voltage is determined when Power ≤ 5V. A software algorithm is used to assess the reliability of the acquired digital power supply voltage, thereby accurately implementing the EPS power management function (V). REG (This refers to the standard output voltage of the LDO chip).

[0034] The main technical solutions are as follows: Figure 1 As shown:

[0035] The LDO chip's input voltage (V_Input) is Power, and its output voltage (V_Output) is V. MCU V MCU Provides the power supply voltage for the MCU chip.

[0036] Resistors R1 and R2 form a voltage divider circuit, with a voltage division ratio of... Resistors R3 and R4 form another voltage divider circuit, with a voltage division ratio of... K1≠K2 (this reflects the variable parameters); the upper end of both voltage divider circuits is connected to Power, and the lower end is connected to GND.

[0037] Dividing voltages U1 = Power·K1, U2 = Power·K2;

[0038] Voltage dividers U1 and U2 are connected to the AD_1 and AD_2 pins of the MCU chip respectively via differential wiring. AD_1 and AD_2 are the pins of the ADC conversion module in the MCU chip.

[0039] The ADC sampling full scale is 2 n The full-scale sampling range of an ADC is represented by the number of bits in the output binary or decimal number. An n-bit output ADC conversion module can distinguish 2... n It can distinguish between different levels of analog input voltage, with the minimum value being full-scale input. The digital values ​​of voltages U1 and U2 after analog-to-digital conversion are AD1 and AD2, respectively. ΔE1 and ΔE2 are common-mode interference. Since the voltage dividers U1 and U2 are implemented using differential routing, ΔE1 = ΔE2 = ΔE.

[0040] Eliminating common-mode interference using differential methods: Variable-parameter differential calculation formula:

[0041]

[0042] It should be noted that since the voltage dividers U1 and U2 are connected to the AD_1 and AD_2 pins of the MCU chip respectively using differential routing, the two common-mode interferences can be considered to be approximately equal. (The purpose of differential routing is to eliminate common-mode interference. The principle is that the two electrical signals are routed in parallel so that they receive the same interference, and the resulting errors are also approximately the same.)

[0043] The value of ΔAD is calculated using the formula for calculating the difference between the upper and lower parameters. Then, the value of ΔAD and 2 are used... n The comparison of |K1-K2| determines whether the EPS power supply voltage is valid or invalid under this state, and whether the ADC sampling value is reliable or unreliable;

[0044] When ΔAD = 2 is detected n When |K1-K2|, prove that Power = V MCU V MCU ≤V REG The MCU chip's power supply voltage is in an undervoltage state. The algorithm determines that the EPS power supply voltage is invalid in this state, the ADC sampling value is unreliable, and the analog signal sampling is not processed.

[0045] When ΔAD > 2 is detected n When |K1-K2|, prove that Power > V MCU V MCU =V REG The MCU chip's power supply voltage is in a normal state. The algorithm determines that the EPS power supply voltage is valid under this state, the ADC sampling value is reliable, and the analog signal sampling is processed normally.

[0046] Under the condition that the ADC sampling value is reliable, the accurate EPS supply voltage can be calculated by an algorithm, and the specific formula is as follows:

[0047]

[0048] In summary, the above technical solutions can accurately determine the validity of the EPS power supply voltage, enable the MCU chip to identify its own power supply voltage status, determine the reliability of the ADC module sampling based on the power supply validity, accurately process the sampled data, avoid false alarms caused by ADC sampling abnormalities due to voltage anomalies, and realize the EPS power management function by acquiring accurate EPS power supply voltage through algorithms.

[0049] Taking a 12V EPS system as an example, the standard output voltage of the LDO chip is V. REGThe voltage is 5V, the MCU operating voltage is 2.7~5.5V, and the ADC sampling full-scale range is 2. 12 =4096, R1=100K, R2=10K, R3=100K, R4=20K, therefore

[0050] The ideal technical solution is as follows:

[0051] When Power ≥ 5V, V MCU =V REG =5V:

[0052]

[0053] = 65.536 × Power;

[0054] When ΔAD>1049, the algorithm calculates that Power>16V, and the EPS is in overvoltage protection state;

[0055] When 590 < ΔAD ≤ 1049, the algorithm calculates that 9V < Power ≤ 16V, ΔAD = 786, and the EPS is working normally.

[0056] When 328 < ΔAD ≤ 590, the algorithm calculates that 5V < Power ≤ 9V, ΔAD = 590, and the EPS is in low voltage protection state.

[0057] When ΔAD = 328, the algorithm calculates Power = 5V. When ΔAD = 328, the EPS power supply voltage is in an invalid state, the ADC sampling value is unreliable, the analog signal sampling is not processed, and the EPS is in standby state.

[0058] The program implements power management by judging the value of ΔAD. If Power < 2.7V, the MCU chip does not work and cannot operate normally. In this state, the EPS is in a power-down state.

[0059] The actual technical solution is as follows:

[0060] In practical product applications, a certain margin is retained in the ΔAD judgment condition to avoid sampling errors caused by factors such as common-mode interference, differential-mode interference, device errors, and LDO chip voltage drop. For example:

[0061] When ΔAD>1081, the algorithm calculates that Power>16.5V, and the EPS is in overvoltage protection state;

[0062] When 557 < ΔAD ≤ 1081, the algorithm calculates that 8.5 < Power ≤ 16.5V, and the EPS works normally.

[0063] When 393 < ΔAD ≤ 557, the algorithm calculates that 6 < Power ≤ 8.5V, and the EPS is in low voltage protection state;

[0064] When 0≤ΔAD≤393, the algorithm calculates that 2.7≤Power<6V, the EPS power supply voltage is in an invalid state, the ADC sampling value is unreliable, the analog signal sampling is not processed, and the EPS is in standby state.

[0065] When Power < 2.7V, the MCU chip does not work and cannot operate normally; in this state, the EPS is in a power-down state.

[0066] Users can set different residual values ​​according to product requirements.

[0067] This is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the effectiveness of a variable-parameter differential EPS power supply voltage, characterized in that, It includes an LDO chip, an MCU chip, and a voltage divider circuit. The voltage divider circuit has two paths, one of which consists of resistors R1 and R2, and divides the voltage by... Voltage division ratio of resistors R1 and R2 The other circuit consists of resistors R3 and R4, and the voltage is... The voltage division ratio of resistors R3 and R4 ≠ The two voltage divider circuits are connected to Power at the top and GND at the bottom. The LDO chip's input voltage is represented by Power, and the output voltage is represented by... , Simultaneously supply power to the MCU chip; The voltage division The MCU chip has two pins for the ADC conversion module, namely AD_1 and AD_2, which are used for voltage division. , Connect to the AD_1 and AD_2 pins of the MCU chip respectively using differential routing; ADC sampling full scale is voltage division , The digital quantities after analog-to-digital conversion are respectively , ,in = , = ,in , This is common-mode interference, due to voltage division. , It uses a differential routing method, therefore = = , = , = ; Eliminating common-mode interference using differential methods: Variable-parameter differential calculation formula: ； The result is obtained by calculating using the formula for the upper variable parametric difference. numerical values use Numerical values ​​and | - The comparison of the 1 and 2 determines whether the EPS power supply voltage is valid or invalid under this state, and whether the ADC sampling value is reliable or unreliable. when = | - At time 1, the algorithm can calculate the result. The MCU chip power supply voltage is in an undervoltage state. The algorithm determines that the EPS power supply voltage is invalid in this state, the ADC sampling value is unreliable, and the analog signal sampling is not processed. when | - At time 1, the algorithm can calculate the result. > , = The MCU chip power supply voltage is in a normal state. The algorithm determines that the EPS power supply voltage is in a valid state under this state, the ADC sampling value is reliable, and the analog signal sampling is processed normally.

2. The method for detecting the effectiveness of variable-parameter differential EPS power supply voltage according to claim 1, characterized in that: The accurate EPS supply voltage is calculated using an algorithm based on the reliable ADC sampling values. The specific formula is as follows: = | - | = | - |.

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