Three-phase current sampling circuit calibration method and system

Abstract

The invention provides a three-phase current sampling circuit calibration method and system, and belongs to the technical field of permanent magnet synchronous motor three-phase current sampling calibration, and the method comprises the following steps: sequentially giving UVW three-phase current through a motor controller; respectively acquiring three-phase current data through a current sampling circuit in the motor controller and an external current sensor; performing linear fitting on the acquired three-phase current data to obtain a current sampling compensation coefficient of the UVW three-phase current sampling circuit; and multiplying the current sampling compensation coefficient by an initial sampling coefficient of the current sampling circuit, and calculating to obtain an actual sampling coefficient. The current sampling compensation coefficient can more accurately reflect the performance of the current sampling circuit under the actual working condition, so that errors and deviation are reduced, and the sampling precision of the current sampling circuit under the large current is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of three-phase current sampling and calibration of permanent magnet synchronous motors, and in particular to a three-phase current sampling circuit calibration method and a system thereof. Background Art

[0002] In the motor drive system, accurate current sampling is crucial to achieve vector control. Only when the sampled current data is accurate can the coordinate transformation be performed correctly, thereby optimizing the motor performance, reducing energy consumption, and improving efficiency. The existing current sampling circuit correction technology is described as follows:

[0003] First, the current sampling circuit correction technology currently widely used is mostly performed under power-on or low-voltage conditions, measuring the output current of the sampling circuit at zero point, that is, the zero-point current calibration test method, to eliminate the deviation of the zero-point current.

[0004] Then, the collected current and the actual current are plotted in a table by tabulating, that is, a series of known current values ​​and their corresponding sampling circuit output data are collected in advance and compiled into a table. When an unknown current needs to be measured, the system will refer to this table to find the closest known current value and estimate the actual current accordingly.

[0005] For example, the Chinese invention patent with application number CN202410177365.5 discloses a method and medium for controlling a wide voltage range of a permanent magnet synchronous motor based on a current lookup table. The method includes obtaining a two-dimensional speed-torque lookup table under rated bus voltage through a full-speed current calibration method; based on the lookup table, a wide voltage range control is achieved by multiplying a given speed by the ratio of the front and rear limiting voltages; and friction torque compensation and sampling delay compensation of three-phase current are performed at different speeds. That is, by considering the bus voltage fluctuations under complex working conditions of electric vehicles, the given speed is multiplied by the variable voltage coefficient to obtain the input speed of the input current lookup table, thereby achieving precise current control of the permanent magnet synchronous motor under different bus voltage conditions.

[0006] However, the existing current sampling circuit correction technology has the following defects:

[0007] On the one hand, the zero-point current calibration test method is mainly aimed at low current conditions, because most current sampling circuits (such as Hall sensors, shunt resistors, etc.) are designed with a certain linear operating range. Within this range, the output signal of the sensor is proportional to the actual current. However, for high current applications, and when the current exceeds this linear range, due to the thermal effect, electromagnetic interference and other problems caused by the increase in current, the original calibration results are no longer applicable, and it is difficult to accurately reflect the true current value, that is, it is impossible to eliminate the sampling deviation under high current conditions.

[0008] On the other hand, the tabulation method is relatively complicated, and the tabulation process is time-consuming and laborious, especially in mass production, each batch of products needs to be calibrated individually, which greatly increases the cost and production cycle. Summary of the invention

[0009] The technical problem to be solved by the present invention is: how to accurately calibrate the three-phase current sampling circuit under strong power conditions?

[0010] In order to solve the above technical problems, the present invention provides a three-phase current sampling circuit calibration method, the method comprising the following steps:

[0011] The UVW three-phase currents are given in sequence through the motor controller;

[0012] The three-phase current data are collected respectively by the current sampling circuit in the motor controller and the external current sensor;

[0013] Performing linear fitting on the collected three-phase current data to obtain a current sampling compensation coefficient of the UVW three-phase current sampling circuit;

[0014] The current sampling compensation coefficient is multiplied by the initial sampling coefficient of the current sampling circuit to calculate and obtain the actual sampling coefficient.

[0015] Furthermore, the UVW three-phase currents are given in sequence by the motor controller, wherein the current values ​​of the given UVW three-phase currents should be large enough to ensure that all possible states of the current sampling circuit in the entire working range are covered.

[0016] Furthermore, three-phase current data are collected respectively by the current sampling circuit in the motor controller and the external current sensor, including:

[0017] The motor controller sends current to the U phase, records the U phase current iU fed back by the U phase current sampling circuit of the motor controller, and the actual U phase current iU collected by the current sensor act ;

[0018] The motor controller sends current to the V phase, records the V phase current iV fed back by the V phase current sampling circuit of the motor controller, and the actual V phase current iV collected by the current sensor act ;

[0019] The motor controller sends current to the W phase, records the W phase current iW fed back by the W phase current sampling circuit of the motor controller, and the actual W phase current iW collected by the current sensor act .

[0020] Furthermore, performing linear fitting on the collected three-phase current data includes:

[0021] The currents iU, iV, and iW fed back by the UVW phase current sampling circuits are respectively used as the X-axis;

[0022] The actual UVW phase current iU collected by the current sensor act 、iV act 、iW act As the Y axis;

[0023] The UVW phase current fitting function is obtained by linear fitting:

[0024]

[0025] Among them, K U is the compensation coefficient of the U-phase current sampling circuit; K V K is the compensation coefficient of the V-phase current sampling circuit; W is the compensation coefficient of the W-phase current sampling circuit.

[0026] Furthermore, the actual sampling coefficient is obtained by calculation, including:

[0027] The compensation coefficient K of the U-phase current sampling circuit is U , initial sampling coefficient iU fac0 Multiply by to calculate the actual sampling coefficient iU of the U-phase current sampling circuit fac ;

[0028] The compensation coefficient K of the V phase current sampling circuit is V , initial sampling coefficient iV fac0 Multiply by to calculate the actual sampling coefficient iV of the V-phase current sampling circuit fac ;

[0029] The compensation coefficient K of the W phase current sampling circuit is W , initial sampling coefficient iW fac0 Multiply by to calculate the actual sampling coefficient iW of the W-phase current sampling circuit fac .

[0030] Furthermore, the initial sampling coefficient of the current sampling circuit is the sampling coefficient of the current sampling circuit itself.

[0031] A three-phase current sampling circuit calibration system is applied to the three-phase current sampling circuit calibration method.

[0032] Further, the calibration system comprises:

[0033] Motor controller, including MCU module, IGBT module and current sampling circuit module;

[0034] A DC bus, connected to a bus terminal of the motor controller;

[0035] A permanent magnet synchronous motor, wherein the UVW three-phase output terminal of the motor controller is connected to the UVW three-phase input terminal of the permanent magnet synchronous motor;

[0036] The current sensor is installed in the UVW three-phase wiring harness in sequence.

[0037] Furthermore, the DC bus is given a high voltage and controls the switch of the IGBT module.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] Under strong electric working conditions, the present invention obtains the current sampling compensation coefficient of the UVW three-phase current sampling circuit by respectively recording the three-phase current collected by the current sampling circuit in the motor controller and the actual three-phase current collected by the external current sensor, and then performs linear fitting on the collected current data, thereby calculating the actual sampling coefficient of the current sampling circuit; the current sampling compensation coefficient can more accurately reflect the performance of the current sampling circuit under actual working conditions, thereby reducing errors and deviations, and improving the sampling accuracy of the current sampling circuit under high current. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a block diagram of the process principles disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the technical scheme and technical effect of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0042] The present invention aims to provide a three-phase current sampling circuit calibration method to solve the problem of accurate calibration of the three-phase current sampling circuit under strong power conditions. The provided method mainly includes the following steps:

[0043] Step 1: Set the UVW three-phase current in sequence through the motor controller

[0044] The motor controller is in the high voltage open state, and the UVW three-phase current is given in sequence, wherein the current value of the UVW three-phase current should be large enough to ensure that all possible states of the current sampling circuit in the entire working range are covered. For example, different current values ​​from zero to rated current can be given to simulate various situations that may be encountered in actual operation.

[0045] Step 2: Collect three-phase current data

[0046] The three-phase current data are collected through the current sampling circuit in the motor controller and the external current sensor. Specifically:

[0047] The motor controller sends current to the U phase, records the U phase current iU fed back by the U phase current sampling circuit of the motor controller, and the actual U phase current iU collected by the current sensor act ;

[0048] The motor controller sends current to the V phase, and records the V phase current iV fed back by the V phase current sampling circuit of the motor controller and the actual V phase current iV collected by the current sensor. act ;

[0049] The motor controller sends current to the W phase, records the W phase current iW fed back by the W phase current sampling circuit of the motor controller, and the actual W phase current iW collected by the current sensor act .

[0050] Step 3: Perform linear fitting on the collected three-phase current data

[0051] Perform linear fitting on the collected three-phase current data to obtain the current sampling compensation coefficient of the UVW three-phase current sampling circuit. Specifically:

[0052] The currents iU, iV, and iW fed back by the UVW phase current sampling circuits are respectively used as the X-axis;

[0053] The actual UVW phase current iU collected by the current sensor act 、V act 、iW act As the Y axis;

[0054] The UVW phase current fitting function is obtained by linear fitting:

[0055]

[0056] Among them, K U is the compensation coefficient of the U-phase current sampling circuit; K V is the compensation coefficient of the V phase current sampling circuit; K W is the compensation coefficient of the W phase current sampling circuit.

[0057] The function of the compensation coefficient of the UVW phase current sampling circuit obtained is to correct the sampling deviation of the current sampling circuit to improve the current control accuracy.

[0058] Step 4: Get the actual sampling coefficient

[0059] The current sampling compensation coefficient is multiplied by the initial sampling coefficient of the current sampling circuit to calculate the actual sampling coefficient.

[0060] Specific:

[0061] The compensation coefficient K of the U phase current sampling circuit U , initial sampling coefficient iU fac0 Multiply them and calculate the actual sampling coefficient iU of the U phase current sampling circuit. fac ;

[0062] The compensation coefficient K of the V phase current sampling circuit V , initial sampling coefficient iV fac0 Multiply them to calculate the actual sampling coefficient iV of the V phase current sampling circuit fac ;

[0063] The compensation coefficient K of the W phase current sampling circuit W , initial sampling coefficient iW fac0 Multiply them and calculate the actual sampling coefficient iW of the W phase current sampling circuit fac .

[0064] The initial sampling coefficient of the current sampling circuit is the sampling coefficient of the current sampling circuit itself.

[0065] The calculated compensation coefficient of the UVW phase current sampling circuit is used to calculate the actual sampling coefficient of the UVW phase current sampling circuit, and the actual sampling coefficient will be used in the subsequent current control algorithm to ensure the stable output of the motor performance.

[0066] The present invention also provides a three-phase current sampling circuit calibration system, which is applied to the above-mentioned three-phase current sampling circuit calibration method. Figure 1 , its calibration system mainly includes: DC bus, motor controller, current sensor and permanent magnet synchronous motor.

[0067] The motor controller includes an MCU module, an IGBT module and a current sampling circuit module. Among them, the MCU module is the core part of the motor controller, responsible for processing various input signals and executing corresponding control algorithms. The IGBT module is an insulated gate bipolar transistor module, which is mainly used to control high voltage and large current. In the motor controller, the IGBT module is mainly used to drive the motor, and the motor is controlled by controlling the switching state of the IGBT. When the IGBT is turned on, the current can generate a rotational torque through the motor; when the IGBT is turned off, the current is cut off and the motor stops running. By accurately controlling the switching state of the IGBT, the motor speed and torque can be accurately controlled. The current sampling circuit module is used to measure the current value when the motor is running, obtain the current signal through the sampling resistor or other sensors, and convert these signals into voltage signals or digital signals. Then, the current sampling circuit sends these signals to the MCU module for processing and analysis. By monitoring the current value, the running state and load condition of the motor can be understood, thereby providing important feedback information for the MCU module to adjust the control strategy and optimize the motor performance.

[0068] Furthermore, the DC bus is connected to the bus terminal of the motor controller; the UVW three-phase output terminal of the motor controller is connected to the UVW three-phase input terminal of the permanent magnet synchronous motor; and the current sensor is sequentially installed on the UVW three-phase harness. The DC bus is given high voltage and controls the switch of the IGBT module.

[0069] The present invention realizes the correction of the three-phase current sampling circuit of the permanent magnet synchronous motor under strong power conditions, which can effectively reduce the sampling deviation of the current sampling circuit and improve the current control accuracy of the permanent magnet synchronous motor.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A three-phase current sampling circuit calibration method, characterized in that: The method comprises the following steps: The UVW three-phase currents are given in sequence through the motor controller; The three-phase current data are collected respectively by the current sampling circuit in the motor controller and the external current sensor; Performing linear fitting on the collected three-phase current data to obtain a current sampling compensation coefficient of the UVW three-phase current sampling circuit; The current sampling compensation coefficient is multiplied by the initial sampling coefficient of the current sampling circuit to calculate and obtain the actual sampling coefficient.

2. The three-phase current sampling circuit calibration method according to claim 1, characterized in that: The UVW three-phase currents are given in sequence by the motor controller, wherein the current values ​​of the given UVW three-phase currents should be large enough to ensure that all possible states of the current sampling circuit in the entire working range are covered.

3. The three-phase current sampling circuit calibration method according to claim 1, characterized in that: The three-phase current data are collected respectively by the current sampling circuit in the motor controller and the external current sensor, including: The motor controller sends current to the U phase, records the U phase current iU fed back by the U phase current sampling circuit of the motor controller, and the actual U phase current iU collected by the current sensor act ; The motor controller sends current to the V phase, records the V phase current iV fed back by the V phase current sampling circuit of the motor controller, and the actual V phase current iV collected by the current sensor act ; The motor controller sends current to the W phase, records the W phase current iW fed back by the W phase current sampling circuit of the motor controller, and the actual W phase current iW collected by the current sensor act .

4. The three-phase current sampling circuit calibration method according to claim 3, characterized in that: The performing linear fitting on the collected three-phase current data comprises: The currents iU, iV, and iW fed back by the UVW phase current sampling circuits are respectively used as the X-axis; The actual UVW phase current iU collected by the current sensor act 、iV act ,iW act As the Y axis; The UVW phase current fitting function is obtained by linear fitting: Among them, K U is the compensation coefficient of the U-phase current sampling circuit; K V K is the compensation coefficient of the V-phase current sampling circuit; W is the compensation coefficient of the W-phase current sampling circuit.

5. The three-phase current sampling circuit calibration method according to claim 4, characterized in that: The actual sampling coefficient is obtained by calculation, including: The compensation coefficient K of the U-phase current sampling circuit is U , initial sampling coefficient iU fac0 Multiply by to calculate the actual sampling coefficient iU of the U-phase current sampling circuit fac ; The compensation coefficient K of the V phase current sampling circuit is V , initial sampling coefficient iV fac0 Multiply by to calculate the actual sampling coefficient iV of the V-phase current sampling circuit fac ; The compensation coefficient K of the W phase current sampling circuit is W , initial sampling coefficient iW fac0 Multiply by to calculate the actual sampling coefficient iW of the W-phase current sampling circuit fac .

6. The three-phase current sampling circuit calibration method according to claim 1, characterized in that: The initial sampling coefficient of the current sampling circuit is the sampling coefficient of the current sampling circuit itself.

7. A three-phase current sampling circuit calibration system, characterized in that: The calibration system is applied to the three-phase current sampling circuit calibration method described in any one of claims 1-6.

8. The three-phase current sampling circuit calibration system according to claim 7, characterized in that: The calibration system comprises: Motor controller, including MCU module, IGBT module and current sampling circuit module; A DC bus, connected to a bus terminal of the motor controller; A permanent magnet synchronous motor, wherein the UVW three-phase output terminal of the motor controller is connected to the UVW three-phase input terminal of the permanent magnet synchronous motor; The current sensor is installed in the UVW three-phase wiring harness in sequence.

9. The three-phase current sampling circuit calibration system according to claim 8, characterized in that: The DC bus provides high voltage and controls the switch of the IGBT module.

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