A power control method for electric motorcycles based on pwm loss management

Abstract

The application discloses a kind of electric motorcycle power control methods based on PWM loss management, comprising the following steps: obtaining running and temperature data, calculating hotspot index and temperature rise rate to generate thermal state quantity;According to the thermal state quantity, the loss reduction control quantity and the output reduction control quantity are graded and output;Combining bus voltage and modulation strategy to calculate the maximum allowable voltage and obtain voltage margin;Based on torque demand and constraint condition, dynamic current distribution is executed to generate d-axis current command and q-axis current command and perform field weakening adjustment;In abnormal condition, execute protection control;The hysteresis, residence time and change rate limit are set to control quantity.The application realizes motor thermal management and PWM loss collaborative control, improves efficiency and operating stability.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle drive control technology, and in particular to a power control method for electric motorcycles based on PWM loss management. Background Technology

[0002] In existing electric motorcycle drive control solutions, for 72V platforms and high-power applications, a vector control architecture based on FOC is usually adopted, combined with static or quasi-dynamic MTPA strategies to achieve current distribution, and SVPWM or overmodulation methods to improve bus voltage utilization. In terms of power stage implementation, a single three-phase inverter bridge structure is often used, with each phase bridge arm consisting of multiple MOSFETs connected in parallel. Temperature sensors are placed near the heat sink or power devices to monitor the temperature status and perform current limiting, torque limiting or derating control when over-temperature risk occurs.

[0003] Most of the aforementioned combined solutions still rely on single-point temperature, average temperature, or simple temperature rise rate as triggering criteria, resulting in a relatively coarse thermal state assessment. This makes it difficult to identify local hotspots and their evolution trends in a timely manner, leading to delayed thermal risk warnings. Existing solutions typically only perform single torque or current limiting after temperature limits are exceeded, lacking hierarchical priority management among switching loss optimization, output derating, and protection actions. This can easily cause sudden power changes, frequent jitter, or conservative control. Thermal management strategies, voltage constraints, and d-axis / q-axis current distribution are mostly designed relatively independently, lacking closed-loop coordination. This makes it difficult to simultaneously ensure power output capability, PWM loss control, and system stability under high load, high speed, and high temperature conditions.

[0004] Therefore, it is necessary to propose a control method that can predict hot spot indicators and temperature rise trends, combine loss reduction and output reduction tiered strategies, and work in conjunction with FOC and dynamic MTPA to achieve smooth power output, efficient thermal management, and better system stability. Summary of the Invention

[0005] One objective of this invention is to propose a power control method for electric motorcycles based on PWM loss management. This invention introduces temperature state assessment, voltage margin constraints, and dynamic current distribution mechanisms, combined with the coordinated adjustment of switching frequency and modulation strategy, to achieve active control of PWM-related losses. It has the advantages of timely response, good thermal management effect, and high operational stability.

[0006] A power control method for an electric motorcycle based on PWM loss management according to an embodiment of the present invention includes the following steps: Acquire data including three-phase current, bus voltage, rotor position or speed signals, torque demand signals, and temperature signals from several temperature sensors on the radiator. Based on the temperature signal, hot spot index and temperature rise rate index are calculated to generate thermal state variables; The system is classified and judged based on hot spot index and temperature rise rate index. When the first-level trigger condition is met, the loss reduction control quantity is output. When the second-level trigger condition is met, the output reduction control quantity is output based on the loss reduction control quantity. The loss reduction control quantity includes the switching frequency and modulation strategy, and the output reduction control quantity includes the current limit value and torque limit value. The maximum allowable voltage is determined based on the bus voltage and modulation strategy, and the stator voltage vector amplitude of the motor is predicted based on the motor operating status to calculate the voltage margin. Dynamic MTPA current command generation is performed based on torque demand signal, speed signal, loss reduction control quantity, output reduction control quantity, maximum allowable voltage, and voltage margin to perform dynamic current distribution calculation and generate d-axis current command and q-axis current command. When the motor stator voltage vector amplitude exceeds the maximum allowable voltage or the voltage margin is less than the preset threshold, the d-axis current command is adjusted in the negative direction. When the d-axis current command reaches the preset limit, the q-axis current command continues to decrease. During the protection process, current limiting, torque limiting, or shutdown control is performed when there is over-temperature, over-current, under-voltage, or sensor malfunction.

[0007] Introduce injection and amplitude limiting, and set hysteresis, dwell time and rate of change limits.

[0008] Optionally, the acquisition of data specifically includes: The three-phase current is obtained based on the single-unit three-phase inverter bridge structure. The switching devices of the upper and lower bridge arms of each phase arm of the three-phase inverter bridge are composed of several parallel MOSFETs. The bus voltage signal is acquired through the DC bus, which is powered by a battery. Obtain rotor position or speed signals, which characterize the motor's operating status; Obtain the torque demand signal, which represents the motor's output torque demand; Temperature signals are collected by several temperature sensors installed on the heat sink. These temperature sensors form a temperature sampling array to obtain temperature data at different locations.

[0009] Optionally, the generated thermal state quantities specifically include: Collect temperature data from several temperature sensors on the radiator at the current moment; multiple temperature sensors form a distributed temperature sampling array, and each temperature sensor establishes a mapping relationship with different regions of the power device. The range of the power device region corresponding to each sensor is determined through pre-calibration or engineering experience. The temperature data from all temperature sensors are compared and processed, and the maximum temperature value or the maximum temperature value in each region after being divided into preset regions is selected as the hot spot index. The hot spot index is differentially calculated within adjacent sampling periods, and the temperature rise rate index is obtained by combining the sampling time interval. The hot spot index and the temperature rise rate index are filtered and limited to obtain the thermal state variables.

[0010] Optionally, the classification determination specifically includes: The hot spot index is compared with the preset first temperature threshold and the second temperature threshold, and the temperature rise rate index is compared with the preset first temperature rise rate threshold and the second temperature rise rate threshold. When the hot spot index does not exceed the first temperature threshold and the temperature rise rate index does not exceed the first temperature rise rate threshold, it is judged to be in a normal state. When the hot spot index exceeds the first temperature threshold or the temperature rise rate index exceeds the first temperature rise rate threshold but does not exceed the second temperature threshold and the second temperature rise rate threshold, it is determined to be a first-level loss reduction state, and the loss reduction control quantity is output. When the hot spot indicator exceeds the second temperature threshold or the temperature rise rate indicator exceeds the second temperature rise rate threshold, it is determined to be in the second-level output reduction state, and the output reduction control quantity is further output on the basis of the loss reduction control quantity. Based on hot spot indicators and temperature rise rate indicators, the loss reduction control quantity and output reduction control quantity are scheduled in segments.

[0011] Optionally, the segmented scheduling specifically includes: Under normal conditions, the current switching frequency, modulation strategy, current limit value, and torque limit value remain unchanged. Under the first-level loss reduction state, at least one of the following methods is used to schedule the loss reduction control quantity: According to the preset temperature range, the range where the hot spot index is located is mapped to the corresponding switching frequency range, and the target switching frequency is calculated according to the position of the hot spot index in the range in a linear proportion. Switch the current modulation strategy to a low-switching-loss modulation method; The loss weighting coefficient is calculated based on the hot spot index and the temperature rise rate index. The total loss function is obtained by weighted summation of different loss items. The d-axis current command and q-axis current command are recalculated based on the total loss function. In the second-level reduced output state, at least one of the following methods can be used to schedule the reduced output control quantity: Based on the preset rate of change coefficient and the current sampling period, the current limit value is multiplied by the rate of change coefficient to obtain the updated current limit value; Based on the preset rate of change coefficient and the current sampling period, the torque limit value is multiplied by the rate of change coefficient to obtain the updated torque limit value; In the first-level loss reduction state and the second-level output reduction state, the scheduling mode is selected or combined according to the changes in hot spot index and temperature rise rate index.

[0012] Optionally, the total loss function specifically includes: The total loss function is obtained through a loss model or by looking up a table. The loss model includes one or more of the following: motor copper loss, iron loss, and power device switching loss. The weights of each loss item are adjusted according to hot spot index or temperature rise rate index.

[0013] Optionally, the calculation of the voltage margin specifically includes: Obtain the bus voltage and determine the maximum allowable voltage based on the modulation upper limit coefficient corresponding to the current modulation strategy; The bus voltage is filtered, and the maximum allowable voltage is corrected by combining the preset voltage reserve to obtain the corrected maximum allowable voltage. Based on the three-phase current and speed signals, combined with motor parameters, the predicted value of the motor stator voltage vector is obtained through FOC decoupling calculation or voltage feedforward calculation. Calculate the magnitude of the motor stator voltage vector based on the predicted value of the motor stator voltage vector; The voltage margin is obtained by calculating the difference between the corrected maximum allowable voltage and the magnitude of the motor stator voltage vector. The voltage margin is filtered and limited.

[0014] Optionally, the dynamic MTPA current command generation specifically includes: Based on the torque demand signal and speed signal, combined with the bus voltage, loss reduction control quantity and output reduction control quantity, dynamic current distribution calculation is performed to obtain the initial d-axis current command and the initial q-axis current command. During the generation of the initial d-axis current command and the initial q-axis current command, the magnitude of the motor stator voltage vector is constrained to not exceed the maximum allowable voltage. Calculate the motor stator voltage vector magnitude based on the initial d-axis current command and the initial q-axis current command, and compare it with the maximum allowable voltage and voltage margin. When the magnitude of the motor stator voltage vector exceeds the maximum allowable voltage or the voltage margin is less than the preset threshold, the d-axis current command will be adjusted in the negative direction. During the adjustment of the d-axis current command, the calculation is recalculated based on the magnitude of the motor stator voltage vector until the magnitude of the motor stator voltage vector meets the constraint condition of not exceeding the maximum allowable voltage. When the d-axis current command reaches the preset limit and the motor stator voltage vector amplitude still does not meet the constraint conditions, the q-axis current command is reduced until the motor stator voltage vector amplitude meets the maximum allowable voltage constraint.

[0015] Optionally, switching the current modulation strategy to a low-switching-loss modulation method specifically includes: When the first-level loss reduction state trigger condition is met, the current modulation strategy is switched from the original PWM modulation mode to the low switching loss modulation mode, which is discontinuous PWM. During the switching process, the original modulation output remains unchanged within the current modulation cycle, and a low switching loss modulation mode is applied in the next modulation cycle.

[0016] Optionally, the protection process specifically includes: During operation, the temperature signal, three-phase current and bus voltage are monitored; when over-temperature, over-current or under-voltage conditions occur, the current limit value and torque limit value are reduced. When a sensor malfunction or abnormal operating condition is detected, the current limit and torque limit values ​​will be adjusted to preset safe values. When the abnormal state persists or the protection condition is met, the drive signal of the three-phase inverter bridge is turned off.

[0017] Optionally, the injection and limiting specifically include: Set change rate limits for switching frequency, modulation strategy, current limit value and torque limit value, and update each control quantity according to the preset change rate in adjacent sampling periods; Set dwell time for the switching frequency and modulation strategy, and keep the switching frequency and modulation strategy from switching until the preset time is reached; Hysteresis ranges are set for switching frequency, modulation strategy, current limit value, and torque limit value. When the control quantity changes, the current control quantity remains unchanged if the change is less than the preset hysteresis range.

[0018] The beneficial effects of this invention are: (1) This invention comprehensively evaluates the temperature status by introducing hot spot index and temperature rise rate index, and makes a graded judgment based on hot spot index and temperature rise rate index. Compared with the control method that only relies on temperature threshold, it can reflect the temperature change trend in advance, realize early intervention on over-temperature risk, improve the response speed of thermal management, and reduce the failure risk of power devices due to excessive temperature rise.

[0019] (2) This invention uses the switching frequency and modulation strategy as loss reduction control quantities. Under the first-level loss reduction state, the switching frequency and modulation strategy are adjusted first. In the dynamic current distribution calculation, a loss weight coefficient is introduced so that the motor copper loss, iron loss and switching loss participate in the optimization calculation. This realizes the coordinated control of PWM related losses and current distribution, effectively reducing system losses and improving overall efficiency while meeting torque requirements.

[0020] (3) By constructing a voltage margin, the present invention considers the voltage margin and the maximum allowable voltage constraint in the dynamic current distribution calculation. When the voltage margin is insufficient or the voltage exceeds the limit, the d-axis current command is adjusted and the q-axis current command is further reduced to achieve a dynamic balance between voltage constraint and output capability. Combined with rate of change limit, hysteresis and dwell time control, the control quantity is avoided from frequent fluctuations, and the stability and reliability of system operation are improved. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of a power control method for electric motorcycles based on PWM loss management proposed in this invention; Figure 2 This is a dynamic MTPA flowchart of a power control method for electric motorcycles based on PWM loss management proposed in this invention. Figure 3 This is a flowchart illustrating the injection and limiting process of a power control method for electric motorcycles based on PWM loss management proposed in this invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0023] refer to Figures 1-3 A power control method for electric motorcycles based on PWM loss management includes the following steps: Acquire data including three-phase current, bus voltage, rotor position or speed signals, torque demand signals, and temperature signals from several temperature sensors on the radiator. Based on the temperature signal, hot spot index and temperature rise rate index are calculated to generate thermal state variables; The system is classified and judged based on hot spot index and temperature rise rate index. When the first-level trigger condition is met, the loss reduction control quantity is output. When the second-level trigger condition is met, the output reduction control quantity is output based on the loss reduction control quantity. The loss reduction control quantity includes the switching frequency and modulation strategy, and the output reduction control quantity includes the current limit value and torque limit value. The maximum allowable voltage is determined based on the bus voltage and modulation strategy, and the stator voltage vector amplitude of the motor is predicted based on the motor operating status to calculate the voltage margin. Dynamic MTPA current command generation is performed based on torque demand signal, speed signal, loss reduction control quantity, output reduction control quantity, maximum allowable voltage, and voltage margin to perform dynamic current distribution calculation and generate d-axis current command and q-axis current command. When the motor stator voltage vector amplitude exceeds the maximum allowable voltage or the voltage margin is less than the preset threshold, the d-axis current command is adjusted in the negative direction. When the d-axis current command reaches the preset limit, the q-axis current command continues to decrease. During the protection process, current limiting, torque limiting, or shutdown control is performed when there is over-temperature, over-current, under-voltage, or sensor malfunction.

[0024] Introduce injection and amplitude limiting, and set hysteresis, dwell time and rate of change limits.

[0025] In this embodiment, data acquisition specifically includes: The three-phase current is obtained based on the single-unit three-phase inverter bridge structure. The switching devices of the upper and lower bridge arms of each phase arm of the three-phase inverter bridge are composed of several parallel MOSFETs. The bus voltage signal is acquired through the DC bus, which is powered by a battery. Obtain rotor position or speed signals, which characterize the motor's operating status; Obtain the torque demand signal, which represents the motor's output torque demand; Temperature signals are collected by several temperature sensors installed on the heat sink. These temperature sensors form a temperature sampling array to obtain temperature data at different locations.

[0026] In this embodiment, the generation of thermal state variables specifically includes: Collect temperature data from several temperature sensors on the radiator at the current moment; The temperature data from all temperature sensors are compared and processed, and the maximum temperature value or the maximum temperature value in each region after being divided into preset regions is selected as the hot spot index. The hot spot index is differentially calculated within adjacent sampling periods, and the temperature rise rate index is obtained by combining the sampling time interval. The hot spot index and the temperature rise rate index are filtered and limited to obtain the thermal state variables.

[0027] Multiple temperature sensors form a distributed temperature sampling array to acquire local temperature information of the motor power devices and heat sinks. Each temperature sensor is mapped to different areas of the power devices, and the corresponding power device area range for each sensor is determined through pre-calibration or engineering experience. During operation, the controller performs a comprehensive analysis of the temperature in each area based on the real-time temperature data from each sensor and the mapping relationships. It selects the maximum temperature value or calculates a weighted index to obtain the hotspot index, thereby reflecting the thermal state of the power devices.

[0028] For hotspot indicators, a first-order low-pass filter is applied, and the filtered value of the hotspot indicator is updated by weighting the current sampled value with the filtering result of the previous period. For the temperature rise rate indicator, a sliding window slope calculation method is used to linearly fit the hotspot indicator over multiple consecutive sampling periods to obtain a smooth temperature rise rate value. Upper and lower thresholds are set for the filtered hotspot indicator and temperature rise rate indicator, respectively. When the calculated result exceeds the upper threshold, it is truncated to the upper threshold, and when it is below the lower threshold, it is truncated to the lower threshold. Consistency judgment is performed on the hotspot indicator and temperature rise rate indicator over multiple consecutive sampling periods. When the change amplitude is less than the preset change threshold, the result of the previous period remains unchanged, thus achieving de-jittering.

[0029] In this embodiment, the classification determination specifically includes: The hot spot index is compared with the preset first temperature threshold and the second temperature threshold, and the temperature rise rate index is compared with the preset first temperature rise rate threshold and the second temperature rise rate threshold. When the hot spot index does not exceed the first temperature threshold and the temperature rise rate index does not exceed the first temperature rise rate threshold, it is judged to be in a normal state. When the hot spot index exceeds the first temperature threshold or the temperature rise rate index exceeds the first temperature rise rate threshold but does not exceed the second temperature threshold and the second temperature rise rate threshold, it is determined to be a first-level loss reduction state, and the loss reduction control quantity is output. When the hot spot indicator exceeds the second temperature threshold or the temperature rise rate indicator exceeds the second temperature rise rate threshold, it is determined to be in the second-level output reduction state, and the output reduction control quantity is further output on the basis of the loss reduction control quantity. Based on hot spot indicators and temperature rise rate indicators, the loss reduction control quantity and output reduction control quantity are scheduled in segments.

[0030] In this embodiment, segmented scheduling specifically includes: Under normal conditions, the current switching frequency, modulation strategy, current limit value, and torque limit value remain unchanged. Under the first-level loss reduction state, at least one of the following methods is used to schedule the loss reduction control quantity: According to the preset temperature range, the range where the hot spot index is located is mapped to the corresponding switching frequency range, and the target switching frequency is calculated according to the position of the hot spot index in the range in a linear proportion. Switch the current modulation strategy to a low-switching-loss modulation method; when the first-level loss reduction state trigger condition is met, switch the current modulation strategy from space vector pulse width modulation to discontinuous pulse width modulation. During the switching process, keep the space vector pulse width modulation output unchanged in the current modulation cycle, and load the discontinuous pulse width modulation in the next modulation cycle. By fixing one phase bridge arm to not perform switching action in each modulation cycle, the number of switching operations is reduced, thereby reducing switching losses. Loss weighting coefficients are calculated based on hotspot and temperature rise rate indicators. A total loss function is obtained by weighted summation of different loss items. The d-axis and q-axis current commands are then recalculated based on this total loss function. Corresponding weighting adjustment coefficients are calculated based on the hotspot and temperature rise rate indicators, and these coefficients are applied to one or more of the motor copper loss, motor iron loss, and switching loss items to obtain weighted loss components. These components are then summed to form the total loss value. During the dynamic current allocation calculation, the total loss value is used as the optimization objective to constrain the d-axis and q-axis currents, resulting in updated d-axis and q-axis current commands.

[0031] In the second-level reduced output state, at least one of the following methods can be used to schedule the reduced output control quantity: Based on the preset rate of change coefficient and the current sampling period, the current limit value is multiplied by the rate of change coefficient to obtain the updated current limit value; Based on the preset rate of change coefficient and the current sampling period, the torque limit value is multiplied by the rate of change coefficient to obtain the updated torque limit value; In the first-level loss reduction state and the second-level output reduction state, the scheduling mode is selected or combined according to the changes in hot spot index and temperature rise rate index.

[0032] In this embodiment, the total loss function specifically includes: The total loss function is obtained through a loss model or by looking up a table. The loss model includes one or more of the following: motor copper loss, iron loss, and power device switching loss. The weights of each loss item are adjusted according to hot spot index or temperature rise rate index.

[0033] In this embodiment, calculating the voltage margin specifically includes: Obtain the bus voltage and determine the maximum allowable voltage based on the modulation upper limit coefficient corresponding to the current modulation strategy; the modulation upper limit coefficient is the maximum voltage utilization ratio that the inverter can output under the current modulation strategy. The bus voltage is filtered, and the maximum allowable voltage is corrected by combining a preset voltage reserve to obtain the corrected maximum allowable voltage. The initial maximum allowable voltage is obtained by multiplying the filtered bus voltage by the modulation upper limit coefficient. The corrected maximum allowable voltage is obtained by subtracting the preset voltage reserve from the initial maximum allowable voltage. The preset voltage reserve is either a pre-calibrated fixed value or a dynamic value calculated proportionally based on changes in the bus voltage. In the dynamic calculation mode, the bus voltage is multiplied by a preset proportional coefficient to obtain the corresponding voltage reserve. The corrected maximum allowable voltage is updated in each sampling period. Based on the three-phase current and speed signals, combined with motor parameters, the predicted value of the motor stator voltage vector is obtained through FOC decoupling calculation or voltage feedforward calculation. The magnitude of the motor stator voltage vector is calculated based on the predicted value of the motor stator voltage vector. The predicted value of the motor stator voltage vector is decomposed into d-axis and q-axis components. The d-axis and q-axis components are squared respectively. The squared results are summed and the summation results are squared to obtain the magnitude of the motor stator voltage vector. The voltage margin is obtained by calculating the difference between the corrected maximum allowable voltage and the magnitude of the motor stator voltage vector. The voltage margin is filtered and limited.

[0034] In this embodiment, the dynamic MTPA current command generation specifically includes: Based on the torque demand signal and speed signal, combined with the bus voltage, loss reduction control quantity, and output reduction control quantity, dynamic current distribution calculation is performed to obtain the initial d-axis current command and the initial q-axis current command. The torque demand signal is converted into the target torque value, and the current operating point is determined by combining the speed signal. Under the constraints of loss reduction control quantity and output reduction control quantity, the current limit value and torque limit value are introduced as constraints into the dynamic current distribution calculation process. Under the constraints, the d-axis current and q-axis current are solved to obtain the initial d-axis current command and the initial q-axis current command. During the generation of the initial d-axis current command and the initial q-axis current command, the magnitude of the motor stator voltage vector is constrained to not exceed the maximum allowable voltage. Calculate the motor stator voltage vector magnitude based on the initial d-axis current command and the initial q-axis current command, and compare it with the maximum allowable voltage and voltage margin. When the magnitude of the motor stator voltage vector exceeds the maximum allowable voltage or the voltage margin is less than the preset threshold, the d-axis current command is adjusted in the negative direction. In each sampling period, the difference between the magnitude of the motor stator voltage vector and the maximum allowable voltage is calculated. The difference is multiplied by the preset d-axis adjustment coefficient to obtain the d-axis current adjustment amount. The d-axis current command is updated by subtracting the d-axis current adjustment amount from the current d-axis current command. The d-axis adjustment coefficient is a preset constant with a value range of 0 to 1. During the adjustment of the d-axis current command, the calculation is recalculated based on the magnitude of the motor stator voltage vector until the magnitude of the motor stator voltage vector meets the constraint that it does not exceed the maximum allowable voltage. In each sampling period, the updated d-axis current command and the current q-axis current command are substituted into the motor stator voltage vector prediction calculation process to obtain a new magnitude of the motor stator voltage vector. When the magnitude of the motor stator voltage vector is still greater than the maximum allowable voltage, the difference calculation and product operation steps are repeated to iteratively update the d-axis current command. When the d-axis current command reaches the preset limit and the motor stator voltage vector amplitude still does not meet the constraint conditions, the q-axis current command is reduced until the motor stator voltage vector amplitude meets the maximum allowable voltage constraint. After the updated d-axis current command reaches the preset limit, the difference between the motor stator voltage vector amplitude and the maximum allowable voltage is calculated in each sampling period. The difference is multiplied by the preset q-axis adjustment coefficient to obtain the q-axis current adjustment amount. The q-axis current adjustment amount is subtracted from the current q-axis current command to obtain the updated q-axis current command. The calculation and update steps are repeated in each sampling period until the motor stator voltage vector amplitude does not exceed the maximum allowable voltage.

[0035] In this embodiment, switching the current modulation strategy to a low-switching-loss modulation method specifically includes: When the first-level loss reduction state trigger condition is met, the current modulation strategy is switched from the original PWM modulation mode to the low switching loss modulation mode, which is discontinuous PWM. During the switching process, the original modulation output remains unchanged within the current modulation cycle, and a low switching loss modulation mode is applied in the next modulation cycle.

[0036] In this embodiment, the protection process specifically includes: During operation, the temperature signal, three-phase current and bus voltage are monitored; when over-temperature, over-current or under-voltage conditions occur, the current limit value and torque limit value are reduced. When a sensor malfunction or abnormal operating condition is detected, the current limit and torque limit values ​​will be adjusted to preset safe values. When the abnormal state persists or the protection condition is met, the drive signal of the three-phase inverter bridge is turned off.

[0037] In this embodiment, injection and limiting specifically include: Set change rate limits for switching frequency, modulation strategy, current limit value and torque limit value, and update each control quantity according to the preset change rate in adjacent sampling periods; Set dwell time for the switching frequency and modulation strategy, and keep the switching frequency and modulation strategy from switching until the preset time is reached; Hysteresis ranges are set for switching frequency, modulation strategy, current limit value, and torque limit value. When the control quantity changes, the current control quantity remains unchanged if the change is less than the preset hysteresis range.

[0038] PWM loss management is reflected in the adjustment of switching losses of power devices through modulation strategies and switching frequencies. Switching frequency and modulation strategy are the core control parameters of PWM modulation. Different modulation strategies correspond to different switching action modes, and different switching frequencies correspond to the number of switching operations per unit time, directly affecting the switching losses of power devices. In the first-level loss reduction state, the switching frequency is reduced and the switching frequency is changed by switching the modulation strategy to reduce the number of switching operations, thereby reducing the switching losses of power devices. In the dynamic current distribution calculation process, switching losses are included as part of the loss model in the weight calculation. The switching loss term is weighted and adjusted according to hot spot index and temperature rise rate index, so that the current distribution result reduces PWM-related losses while meeting torque requirements. Through the coordinated adjustment of switching frequency, modulation strategy, and switching loss term in the loss model, power control based on PWM losses is achieved.

[0039] This invention is applied to a 72V high-power platform to meet the requirements of continuous power and peak power operation. The controller power stage adopts a single three-phase inverter bridge structure, with each phase bridge arm consisting of at least six MOSFETs connected in parallel to support high current output and ensure reliability. To achieve precise thermal management and over-temperature protection, multiple temperature sensors are arranged on the heat sink to form a distributed temperature sampling array, simultaneously collecting operating parameters such as three-phase phase current, bus voltage, and rotor position or speed signals. Under conditions of ramping, acceleration, prolonged high load, and high ambient temperature, the local temperature rise of power devices and heat sinks may increase rapidly. Therefore, real-time monitoring and prediction of hotspot areas are required to provide a reliable engineering basis for thermoelectric synergistic graded derating control.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A power control method for electric motorcycles based on PWM loss management, characterized in that, Includes the following steps: Acquire data including three-phase current, bus voltage, rotor position or speed signals, torque demand signals, and temperature signals from several temperature sensors on the radiator. Based on the temperature signal, hot spot index and temperature rise rate index are calculated to generate thermal state variables; The system is classified and judged based on hot spot index and temperature rise rate index. When the first-level trigger condition is met, the loss reduction control quantity is output. When the second-level trigger condition is met, the output reduction control quantity is output based on the loss reduction control quantity. The loss reduction control quantity includes the switching frequency and modulation strategy, and the output reduction control quantity includes the current limit value and torque limit value. The maximum allowable voltage is determined based on the bus voltage and modulation strategy, and the stator voltage vector amplitude of the motor is predicted based on the motor operating status to calculate the voltage margin. Dynamic MTPA current command generation is performed based on torque demand signal, speed signal, loss reduction control quantity, output reduction control quantity, maximum allowable voltage, and voltage margin to perform dynamic current distribution calculation and generate d-axis current command and q-axis current command. When the motor stator voltage vector amplitude exceeds the maximum allowable voltage or the voltage margin is less than the preset threshold, the d-axis current command is adjusted in the negative direction. When the d-axis current command reaches the preset limit, the q-axis current command continues to decrease. During the protection process, current limiting, torque limiting, or shutdown control is performed when there is over-temperature, over-current, under-voltage, or sensor malfunction. Introduce injection and amplitude limiting, and set hysteresis, dwell time and rate of change limits.

2. The power control method for electric motorcycles based on PWM loss management according to claim 1, characterized in that, The data acquisition specifically includes: The three-phase current is obtained based on the single-unit three-phase inverter bridge structure. The switching devices of the upper and lower bridge arms of each phase arm of the three-phase inverter bridge are composed of several parallel MOSFETs. The bus voltage signal is acquired through the DC bus, which is powered by a battery. Acquire rotor position or speed signals, which characterize the motor's operating status; Obtain the torque demand signal, which represents the motor's output torque demand; Temperature signals are collected by several temperature sensors installed on the heat sink. These temperature sensors form a temperature sampling array to obtain temperature data at different locations.

3. The power control method for electric motorcycles based on PWM loss management according to claim 2, characterized in that, The generated thermal state quantities specifically include: Collect temperature data from several temperature sensors on the radiator at the current moment; multiple temperature sensors form a distributed temperature sampling array, and each temperature sensor establishes a mapping relationship with different regions of the power device. The range of the power device region corresponding to each sensor is determined through pre-calibration or engineering experience. The temperature data from all temperature sensors are compared and processed, and the maximum temperature value or the maximum temperature value in each region after being divided into preset regions is selected as the hot spot index. The hot spot index is differentially calculated within adjacent sampling periods, and the temperature rise rate index is obtained by combining the sampling time interval. The hot spot index and the temperature rise rate index are filtered and limited to obtain the thermal state variables.

4. The power control method for an electric motorcycle based on PWM loss management according to claim 3, characterized in that, The classification determination specifically includes: The hot spot index is compared with the preset first temperature threshold and the second temperature threshold, and the temperature rise rate index is compared with the preset first temperature rise rate threshold and the second temperature rise rate threshold. When the hot spot index does not exceed the first temperature threshold and the temperature rise rate index does not exceed the first temperature rise rate threshold, it is judged to be in a normal state. When the hot spot index exceeds the first temperature threshold or the temperature rise rate index exceeds the first temperature rise rate threshold but does not exceed the second temperature threshold and the second temperature rise rate threshold, it is determined to be a first-level loss reduction state, and the loss reduction control quantity is output. When the hot spot indicator exceeds the second temperature threshold or the temperature rise rate indicator exceeds the second temperature rise rate threshold, it is determined to be in the second-level output reduction state, and the output reduction control quantity is further output on the basis of the loss reduction control quantity. Based on hot spot indicators and temperature rise rate indicators, the loss reduction control quantity and output reduction control quantity are scheduled in segments.

5. The power control method for an electric motorcycle based on PWM loss management according to claim 4, characterized in that, The segmented scheduling specifically includes: Under normal conditions, the current switching frequency, modulation strategy, current limit value, and torque limit value remain unchanged. Under the first-level loss reduction state, at least one of the following methods is used to schedule the loss reduction control quantity: According to the preset temperature range, the range where the hot spot index is located is mapped to the corresponding switching frequency range, and the target switching frequency is calculated according to the position of the hot spot index in the range in a linear proportion. Switch the current modulation strategy to a low-switching-loss modulation method; The loss weighting coefficient is calculated based on the hot spot index and the temperature rise rate index. The total loss function is obtained by weighted summation of different loss items. The d-axis current command and q-axis current command are recalculated based on the total loss function. In the second-level reduced output state, at least one of the following methods can be used to schedule the reduced output control quantity: Based on the preset rate of change coefficient and the current sampling period, the current limit value is multiplied by the rate of change coefficient to obtain the updated current limit value; Based on the preset rate of change coefficient and the current sampling period, the torque limit value is multiplied by the rate of change coefficient to obtain the updated torque limit value; In the first-level loss reduction state and the second-level output reduction state, the scheduling mode is selected or combined according to the changes in hot spot index and temperature rise rate index.

6. The power control method for an electric motorcycle based on PWM loss management according to claim 5, characterized in that, The total loss function specifically includes: The total loss function is obtained through a loss model or by looking up a table. The loss model includes one or more of the following: motor copper loss, iron loss, and power device switching loss. The weights of each loss item are adjusted according to hot spot index or temperature rise rate index.

7. The power control method for an electric motorcycle based on PWM loss management according to claim 5, characterized in that, The calculation of voltage margin specifically includes: Obtain the bus voltage and determine the maximum allowable voltage based on the modulation upper limit coefficient corresponding to the current modulation strategy; The bus voltage is filtered, and the maximum allowable voltage is corrected by combining the preset voltage reserve to obtain the corrected maximum allowable voltage. Based on the three-phase current and speed signals, combined with motor parameters, the predicted value of the motor stator voltage vector is obtained through FOC decoupling calculation or voltage feedforward calculation. Calculate the magnitude of the motor stator voltage vector based on the predicted value of the motor stator voltage vector; The voltage margin is obtained by calculating the difference between the corrected maximum allowable voltage and the magnitude of the motor stator voltage vector. The voltage margin is filtered and limited.

8. The power control method for an electric motorcycle based on PWM loss management according to claim 7, characterized in that, The dynamic MTPA current command generation specifically includes: Based on the torque demand signal and speed signal, combined with the bus voltage, loss reduction control quantity and output reduction control quantity, dynamic current distribution calculation is performed to obtain the initial d-axis current command and the initial q-axis current command. During the generation of the initial d-axis current command and the initial q-axis current command, the magnitude of the motor stator voltage vector is constrained to not exceed the maximum allowable voltage. Calculate the motor stator voltage vector magnitude based on the initial d-axis current command and the initial q-axis current command, and compare it with the maximum allowable voltage and voltage margin. When the magnitude of the motor stator voltage vector exceeds the maximum allowable voltage or the voltage margin is less than the preset threshold, the d-axis current command will be adjusted in the negative direction. During the adjustment of the d-axis current command, the calculation is recalculated based on the magnitude of the motor stator voltage vector until the magnitude of the motor stator voltage vector meets the constraint condition of not exceeding the maximum allowable voltage. When the d-axis current command reaches the preset limit and the magnitude of the motor stator voltage vector still does not meet the constraint conditions, the q-axis current command is reduced until the magnitude of the motor stator voltage vector meets the maximum allowable voltage constraint.

9. The power control method for an electric motorcycle based on PWM loss management according to claim 8, characterized in that, The specific steps of switching the current modulation strategy to a low-switching-loss modulation method include: When the first-level loss reduction state trigger condition is met, the current modulation strategy is switched from the original PWM modulation mode to the low switching loss modulation mode, which is discontinuous PWM. During the switching process, the original modulation output remains unchanged within the current modulation cycle, and a low switching loss modulation mode is applied in the next modulation cycle.

10. The power control method for an electric motorcycle based on PWM loss management according to claim 9, characterized in that, The protection process and the introduction of injection and limiting specifically include: During operation, the temperature signal, three-phase current and bus voltage are monitored; when over-temperature, over-current or under-voltage conditions occur, the current limit value and torque limit value are reduced. When a sensor malfunction or abnormal operating condition is detected, the current limit and torque limit values ​​will be adjusted to preset safe values. When the abnormal state persists or the protection condition is met, the drive signal of the three-phase inverter bridge is turned off; Set change rate limits for switching frequency, modulation strategy, current limit value and torque limit value, and update each control quantity according to the preset change rate in adjacent sampling periods; Set dwell time for the switching frequency and modulation strategy, and keep the switching frequency and modulation strategy from switching until the preset time is reached; Hysteresis ranges are set for switching frequency, modulation strategy, current limit value, and torque limit value. When the control quantity changes, the current control quantity remains unchanged if the change is less than the preset hysteresis range.

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