In modern AC drive and servo systems, voltage-type AC-DC-AC inverters are widely used. The performance of the rectifier at the input end of such inverters is crucial [1]. On the one hand, the rectifier needs to provide the inverter with high-quality DC voltage and have anti-interference capability; on the other hand, the rectifier should not cause harmonic pollution and reactive power pollution to the power grid; in addition, the regenerative energy fed back to the DC side when the motor brakes should be able to be fed back to the power grid. PWM rectifiers are the ideal choice to achieve the above performance [2]. Among the control strategies of many PWM rectifiers, voltage-oriented vector control has received widespread attention due to its advantages such as no steady-state error in the current and the ability to achieve separate decoupling control of the active and reactive components of the current. However, voltage-oriented vector control is based on the idea of ​​coordinate rotation transformation, which has a relatively large computational load. In order to meet the real-time requirements of the control system, it puts forward high requirements on the computing resources of the CPU [3]. This paper presents a design scheme for a voltage-oriented vector control system for a PWM rectifier based on the high-performance DSP chip TMS320F2812 using a fully digital method. The aim is to achieve excellent dynamic and static control performance while making the system small in size, highly integrated, and strong anti-interference capability. Voltage-oriented vector control principle The main circuit of the three-phase PWM rectifier is shown in Figure 1. The additional resistance of the inductor is ignored in Figure 1. [align=center] Figure 1 Main circuit of three-phase PWM rectifier[/align] In the three-phase stationary coordinate system, the mathematical model of the PWM rectifier is [4] (1) In order to perform vector control, it needs to be transformed into the dq two-phase synchronous rotating coordinate system. The mathematical model after the transformation is (2) It can be seen that in the dq coordinate system, the variables of the quadrature and direct axes are coupled to each other. It is impossible to control the quadrature and direct axis current separately by controlling the quadrature and direct axis components of the rectifier inverter voltage. Therefore, it is necessary to introduce feedforward decoupling control in the control loop. When the current loop adopts PI regulation and introduces feedforward decoupling control, the control equations for ud and uq are as follows: (3) Substituting equation (3) into equation (2), we can obtain the following equation (4). It can be seen that the quadrature and direct axis currents no longer have a coupling relationship, and the actual quadrature and direct axis currents can follow their own given current changes. Voltage-oriented vector control is a control method based on dq coordinate transformation. Since sinusoidal quantities are direct quantities in the synchronous rotating coordinate system, vector control can convert the control of AC quantities ua, ub, uc and ia, ib, ic into the control of direct quantities ud, uq and id, iq. Since the PI controller can realize the regulation of DC quantities without steady-state error and can control the active and reactive components separately, vector control can improve the dynamic and static performance of the system. [align=center] Figure 2 Block diagram of voltage-oriented vector control principle of PWM rectifier[/align] The block diagram of the PWM rectifier vector control system used in this paper is shown in Figure 2. The system is oriented according to the grid voltage vector, meaning the d-axis of the synchronous rotating coordinate system is chosen in the direction of the grid voltage vector, and the q-axis leads the d-axis by 90°. As shown in Figure 2, the system adopts a double closed-loop structure with an outer DC bus voltage loop and an inner current loop. The outer voltage loop controls the DC bus voltage to maintain its stability and provide disturbance rejection, while also allowing for adjustable output voltage. The voltage loop output serves as the active current reference id*, and to achieve unity power factor operation, the reactive current reference iq* is set to 0. The reference current is compared with the actual current, and after passing through the current regulator, it serves as the reference value for the grid-side voltage. PWM generation uses the SVPWM method, which is easily implemented using a TMS320F2812. Design of Voltage Oriented Vector Control System Based on DSP As can be seen from the above analysis, the voltage oriented vector control strategy requires rotational coordinate transformation and also includes three closed-loop regulators, which requires a lot of calculation. The DSP chip TMS320F2812 is a high-speed digital processing chip with rich peripherals including AD conversion and PWM output. The main frequency can reach 150MHz, which can well meet the requirements of large amount of calculation and high real-time performance of the control system [5]. Based on the above voltage vector control principle, this paper designs a PWM rectifier vector control system based on TMS320F2812. The hardware and software design will be elaborated below. [align=center] Figure 3 Circuit structure diagram of the vector control system of PWM rectifier[/align] The hardware structure block diagram of the system is shown in Figure 3. The whole system consists of three subsystems: main circuit, control circuit and signal acquisition circuit. The main circuit includes a filter inductor, power switching devices, and a DC filter capacitor, primarily responsible for power conversion to achieve bidirectional energy flow. The control circuit employs a DSP-based digital design, significantly simplifying hardware design. Its main task is to implement vector control algorithms and ensure safe and reliable system operation, thereby achieving sinusoidal grid-side current and synchronizing it with the grid voltage. The signal acquisition subsystem includes grid-side voltage and current detection, as well as DC voltage detection, converting high-voltage signals into 0-3.3V analog signals compatible with the DSP chip's level. The power switching devices in the main circuit utilize Mitsubishi's intelligent power module (IPM) PS21867. This IPM integrates the power switching devices and drive circuitry, optimizing the gate drive circuitry, eliminating the need for complex drive circuit design. The DSP output signal drives the switching devices through a simple level conversion circuit. Furthermore, the IPM integrates fault detection circuits for control power supply undervoltage, overcurrent, and overheating. The IPM can operate in three states: normal drive, short-circuit protection, and control power supply undervoltage protection. If a protection circuit in the IPM operates, the input signal of the corresponding IGBT unit will be blocked and a fault signal FO will be output. Therefore, even if a load accident occurs or improper use occurs, the IPM itself can be guaranteed to be undamaged. The control circuit is based on the TMS320F2812 and mainly includes a DSP chip, a display circuit and an analog signal level conversion circuit. The TMS320F2812 is a 32-bit fixed-point DSP tailored by TI for motor control. The significant feature of this chip is that it has two event managers suitable for motor control. Each event manager has two general-purpose timers, six PWM outputs with dead-time function, and one SVPWM hardware generation unit. Compared with another motor control chip from TI, the LF2407A, its main frequency is higher, reaching 150MHz, and therefore it can better meet the real-time requirements [5]. [align=center]Figure 4 Flowchart of the PWM rectifier control strategy software[/align] Figure 4 is the flowchart of the voltage-oriented vector control software program. All algorithms are implemented in the DSP by software, mainly including voltage and current AD conversion and digital filtering algorithms, voltage orientation angle calculation, DC voltage acquisition and closed-loop regulation, current rotation coordinate transformation and corresponding closed-loop regulation, and SVPWM algorithm, etc. Conclusion The PWM rectifier based on voltage-oriented vector control has advantages such as good sinusoidal input current, system operation at unity power factor, free bidirectional energy transfer, and excellent dynamic and static control performance. This paper introduces a PWM rectifier vector control system based on the DSP chip TMS320F2812 and gives specific software and hardware design methods. The DSP-based system design scheme can greatly reduce the design workload and has the advantages of small size, strong anti-interference ability, and high reliability.