A method for loss optimization of ring bus based on space vector modulation
By dynamically allocating zero-vector time in space vector modulation and combining it with particle swarm optimization algorithm, the problems of high loss and severe local heating of the annular busbar are solved, the busbar loss is optimized, and the stability and life of the motor driver are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHEAST UNIV
- Filing Date
- 2026-05-20
- Publication Date
- 2026-06-19
Smart Images
Figure CN122247160A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of motor drive and power electronics technology, specifically relating to a method for optimizing annular bus losses based on space vector modulation, applicable to DC bus loss suppression in high power density integrated joint motor drivers, dual three-phase or six-phase motor inverters. Background Technology
[0002] In high-power-density integrated articulated motor drives, a ring-shaped DC bus and distributed capacitors have become important solutions for improving power density and structural compactness. Because the ring-shaped bus has a segmented distributed topology, stray inductance, bus resistance, and distributed capacitors exhibit strong electrical coupling. Traditional space vector pulse width modulation (SVPWM) defaults to evenly distributing the zero-vector time, failing to consider the distributed parameter characteristics and current path differences of the ring-shaped bus. This leads to problems such as localized current concentration, high losses, and severe heat generation on the bus.
[0003] Existing optimization methods are mostly based on stacked buses or lumped parameter models and only address the stress borne by capacitors, failing to accurately reflect the segmented loss characteristics of a ring topology. Some modulation optimization strategies only focus on output harmonic suppression, without optimizing zero-vector time allocation to minimize the overall loss of the ring bus. Furthermore, traditional methods struggle to achieve coordinated optimization of bus losses and capacitor current stress without increasing the number of switching operations or altering the hardware structure.
[0004] Therefore, for the purpose of suppressing losses in a ring-shaped DC bus, there is an urgent need for a zero-vector optimization method based on SVPWM that can be directly embedded into existing control systems and is applicable to the bus loss optimization method of multi-phase motor drivers without increasing switching losses. Summary of the Invention
[0005] Technical Problems: This invention addresses the following shortcomings of existing technologies: 1. Traditional SVPWM employs a zero-vector equalization strategy, failing to consider the distributed parameters and segmented loss characteristics of the annular DC bus, resulting in high bus losses or severe localized heating; 2. Existing loss optimization methods cannot maintain the effective vector action time unchanged, making it difficult to minimize bus losses without increasing the number of switching operations; 3. There is a lack of a zero-vector time allocation optimization model targeting the overall loss of the annular bus. Therefore, this invention proposes an annular bus loss optimization method based on space vector modulation.
[0006] Technical Solution: To solve the above-mentioned technical problems, the present invention adopts a method for optimizing the loss of a ring bus based on space vector modulation, which includes: establishing a loss calculation model based on a ring DC bus and distributed capacitors; keeping the effective vector action time unchanged in space vector pulse width modulation (SVPWM) and adjusting the time allocation ratio of the zero vector; constructing an objective function with the goal of minimizing the overall loss of the ring bus; obtaining the optimal zero vector ratio through an optimization algorithm; reconstructing the switching sequence according to the optimal zero vector time allocation and outputting the drive signal to achieve the optimization of the ring bus loss.
[0007] in,
[0008] The loss calculation model is based on the effective value of the bus current of each sub-topology. With bus resistance Calculate the total copper loss of the ring bus to obtain the ring bus loss over one switching cycle. The specific definition is as follows:
[0009] ,
[0010] in, It's busbar loss. It is the current in the ring bus. It is a ring bus resistor.
[0011] The time allocation ratio for adjusting the zero vector is adjusted during the total zero vector action time. Adjustment while keeping it unchanged and Duration of action of two zero vectors and The specific definition is as follows:
[0012] ,
[0013] in, It is the zero vector Duration of action It is the zero vector Duration of action It is the total action time of the zero vector.
[0014] The optimization objective is to minimize the overall loss of the annular busbar. The constraints include that the effective vector time remains unchanged, the zero vector time is non-negative, and the sum of the action times of all vectors is one switching cycle.
[0015] The optimization algorithm used is Particle Swarm Optimization (PSO), with the zero vector time change or proportion as the optimization variable. The specific definition of PSO is as follows:
[0016] ,
[0017] in, ω represents the velocity of the i-th particle in the j-th iteration, where ω represents the inertial weight of the particle's own motion. It represents the velocity of the i-th particle in the (j-1)-th iteration, where c1 and c2 represent the empirical coefficient of the particle itself and the empirical coefficient of the particle swarm, respectively. and It is any floating-point number in the interval [0,1]. and Let be the optimal position of the i-th particle itself and the optimal position of the entire particle swarm, respectively. It is the position of the i-th particle in the j-th iteration. It is the position of the (j-1)th iteration of the i-th particle.
[0018] The zero vector proportion optimization is performed independently once in each switching cycle to obtain the optimal zero vector allocation scheme for the current cycle.
[0019] When reconstructing the switching sequence, only the zero vector timing is adjusted, without changing the order and timing of the effective vectors.
[0020] After the drive signal is output, the operating conditions are re-acquired in the next switching cycle and the zero vector ratio is iteratively optimized to form a periodic closed loop.
[0021] The method is applicable to dual three-phase or six-phase integrated articulated motor drives, and the optimization effect is most significant within a medium modulation ratio range.
[0022] Beneficial effects: This invention achieves ring DC bus loss suppression solely through dynamic allocation optimization of the zero vector action time in the space vector modulation strategy, without requiring modifications to the driver hardware structure or adding extra inverter switching actions and losses. It is easily embedded in existing motor drive control systems. This invention fully adapts to the segmented distributed parameter characteristics and multi-branch current coupling rules of the ring DC bus, optimizing the zero vector ratio with the goal of minimizing overall bus loss. This effectively improves the problems of local current concentration, high losses, and severe local heating in the ring bus. This invention has strong adaptability to operating conditions, exhibiting good optimization effects within the conventional modulation ratio operating range. It can be applied to dual three-phase or six-phase multi-phase integrated articulated motor drive scenarios, significantly improving the operational stability, thermal safety, and overall service life of high power density power electronic devices. Attached Figure Description
[0023] Figure 1 This is a flowchart of the annular bus loss optimization method based on space vector modulation according to the present invention. Detailed Implementation
[0024] The present invention provides a method for optimizing the loss of a ring bus based on space vector modulation, comprising:
[0025] 1. Establish a loss calculation model for a ring-shaped DC bus, based on the bus current. With bus resistance Calculate total bus losses ;
[0026] 2. In SVPWM, the effective vector action time remains constant, and the total zero vector action time is... Remain unchanged, only adjust the action time of the two zero vectors. and The allocation ratio;
[0027] 3. Construct an optimization objective function with the goal of minimizing the overall loss of the annular busbar, and set vector time legal constraints;
[0028] 4. An optimization algorithm is used to find the optimal zero vector ratio to obtain the optimal zero vector allocation scheme for each switching cycle;
[0029] 5. Reconstruct the switching sequence based on the optimal zero-vector time and output the inverter drive signal to achieve optimization of the ring bus loss.
[0030] The present invention will be further described in detail with reference to the accompanying drawings.
[0031] This invention relates to a method for optimizing the loss of a ring bus based on space vector modulation. The specific implementation steps are as follows:
[0032] Step 1:
[0033] Based on the segmented topology of the ring DC bus and distributed capacitors, a loss calculation model for the ring DC bus is established, relying on the resistance of each segment of the bus. and real-time current RMS value Accurate calculation of the losses in each segment of the ring bus and the total overall loss within a single switching cycle provides a quantitative evaluation basis for subsequent optimization. The specific definitions are as follows:
[0034] ,
[0035] in, It's busbar loss. It is the current in the ring bus. It is a ring bus resistor.
[0036] Step 2:
[0037] In the traditional space vector modulation framework, the duration of each effective voltage vector is kept constant, while the total duration of the zero vector within the switching cycle remains unchanged. Only the distribution ratio and duration of the two types of zero vectors are dynamically adjusted, without altering the original modulation output fundamental characteristics and harmonic performance. The specific definitions are as follows:
[0038] ,
[0039] in, It is the zero vector Duration of action It is the zero vector Duration of action It is the total action time of the zero vector.
[0040] Step 3:
[0041] The objective function is constructed with the goal of minimizing the overall loss of the annular DC bus. Complete optimization constraints are established by combining the constraints of switching cycle duration, non-negativity of the action time of each vector, and constant effective vector duration, thus forming a parameter optimization model with zero vector time allocation.
[0042] Step 4:
[0043] The particle swarm optimization (PSO) algorithm is used to optimize the zero-vector allocation parameters within a cycle, resulting in the optimal zero-vector time allocation scheme that minimizes bus losses under the current operating conditions. The specific definition of the optimization algorithm is as follows:
[0044] ,
[0045] in, ω represents the velocity of the i-th particle in the j-th iteration, where ω represents the inertial weight of the particle's own motion. It represents the velocity of the i-th particle in the (j-1)-th iteration, where c1 and c2 represent the empirical coefficient of the particle itself and the empirical coefficient of the particle swarm, respectively. and It is any floating-point number in the interval [0,1]. and Let be the optimal position of the i-th particle itself and the optimal position of the entire particle swarm, respectively. It is the position of the i-th particle in the j-th iteration. It is the position of the (j-1)th iteration of the i-th particle.
[0046] Step 5:
[0047] Based on the optimal zero-vector action time obtained through optimization, the space vector modulation switching timing is rearranged to generate the corresponding inverter drive pulse signal and apply it to the motor inverter. Without increasing the switching action or changing the hardware structure, the overall loss of the ring DC bus is reduced, which can meet the long-term stable operation requirements of dual three-phase or six-phase integrated motor drivers.
Claims
1. A method for optimizing the loss of a ring bus based on space vector modulation, characterized in that, The optimization method includes: establishing a loss calculation model based on the annular DC bus and distributed capacitors; keeping the effective vector action time unchanged in space vector pulse width modulation (SVPWM) and adjusting the time allocation ratio of the zero vector; constructing an objective function with the goal of minimizing the overall loss of the annular bus; obtaining the optimal zero vector ratio through optimization algorithms; reconstructing the switching sequence according to the optimal zero vector time allocation and outputting the drive signal to achieve annular bus loss optimization.
2. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 1, characterized in that, The loss calculation model is based on the effective value of the bus current of each sub-topology. With bus resistance Calculate the total copper loss of the ring bus to obtain the ring bus loss over one switching cycle. The specific definition is as follows: ， in, It's busbar loss. It is the current in the ring bus. It is a ring bus resistor.
3. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 2, characterized in that, The time allocation ratio for adjusting the zero vector is adjusted during the total zero vector action time. Adjustment while keeping it unchanged and Duration of action of two zero vectors and The specific definition is as follows: ， in, It is the zero vector Duration of action It is the zero vector Duration of action It is the total action time of the zero vector.
4. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 3, characterized in that, The optimization objective is to minimize the overall loss of the annular busbar. The constraints include that the effective vector time remains unchanged, the zero vector time is non-negative, and the sum of the action times of all vectors is one switching cycle.
5. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 4, characterized in that, The optimization algorithm used is Particle Swarm Optimization (PSO), with the zero vector time change or proportion as the optimization variable. The specific definition of PSO is as follows: ， in, ω represents the velocity of the i-th particle in the j-th iteration, where ω represents the inertial weight of the particle's own motion. It represents the velocity of the i-th particle in the (j-1)-th iteration, where c1 and c2 represent the empirical coefficient of the particle itself and the empirical coefficient of the particle swarm, respectively. and It is any floating-point number in the interval [0,1]. and Let be the optimal position of the i-th particle itself and the optimal position of the entire particle swarm, respectively. It is the position of the i-th particle in the j-th iteration. It is the position of the (j-1)th iteration of the i-th particle.
6. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 5, characterized in that, The zero vector proportion optimization is performed independently once in each switching cycle to obtain the optimal zero vector allocation scheme for the current cycle.
7. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 1, characterized in that, When reconstructing the switching sequence, only the zero vector timing is adjusted, without changing the order and timing of the effective vectors.
8. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 1, characterized in that, After the drive signal is output, the operating conditions are re-acquired in the next switching cycle and the zero vector ratio is iteratively optimized to form a periodic closed loop.
9. The method for optimizing the loss of a ring bus based on space vector modulation according to claim 1, characterized in that, The method is applicable to dual three-phase or six-phase integrated articulated motor drives, and the optimization effect is most significant within a medium modulation ratio range.